The NBA will implement a coach's challenge at the upcoming summer leagues and anticipates using the rule during the 2019-20 regular season as part of a pilot program, per a memo sent to teams this morning and obtained by ESPN.

Coaches will get only one challenge per game, whether it is successful or unsuccessful, according to the memo. They can use it to challenge only called fouls, goaltending, basket interference and plays when the ball is knocked out of bounds, the memo says. The NBA has tested this version of the challenge system in the G League over the past two seasons.

Coaches must have a timeout remaining to use a challenge. The team must call a timeout immediately after the event it would like to challenge, and the coach must "twirl his/her index finger toward the referees" to signal for the challenge, the memo states. If the challenge is successful, the team retains the timeout it used to stop play. If the challenge is unsuccessful, it loses that timeout.

The crew chief among the referees will determine the outcome of challenges involving called fouls. The NBA Replay Center will decide all other challenges. Any technical flagrant fouls that occur during or "immediately after" the call being challenged will stand regardless of the outcome of the challenge, the memo says.

Both the league office and the NBA's competition committee, composed of coaches, front-office executives and players, are recommending the league's board of governors approve the rule for the 2019-20 season "on a trial basis," the memo says.

"We anticipate this rule will be in effect in the NBA next season as part of a one-year pilot program," the memo states.

When the league and its teams discussed the challenge concept at the general managers meetings in May in Chicago, there was some trepidation about allowing coaches to challenge called fouls, per sources who spoke to ESPN.com at the time. Backers of a more expansive challenge system have apparently won that argument for now. Coaches will not be able to challenge uncalled fouls. Any attempt to expand the challenge rule into that area would result in a bigger, and likely longer, fight, sources said.

Also in the memo:

• The NBA during summer leagues will use the G League's "transition take foul" rule, which penalizes intentional fouls that stop fast-break opportunities but do not qualify as clear path fouls. The fouled team will get one free throw -- to be attempted by a player of its choice from among the five in the game at the time of the foul -- and retain possession of the ball, the memo states. There has been agitation in favor of the NBA adopting this rule.

• The NBA during the Las Vegas Summer League will experiment with a so-called "connected basketball" -- an official NBA game ball with a motion-tracking chip inside of it.

Approving the proposed challenge rule for use in the 2019-20 regular season would require support from two-thirds of the league's teams in a formal vote of the board of governors. The league will submit it to a vote before the full board on July 9. "Based on the feedback we have received, we expect it to be adopted," the memo says.

On the day after the Golden State Warriors lost the NBA Finals, hours after he walked with another limping star toward a gruesome MRI, Bob Myers woke up early to take his daughter to summer camp.

Myers, the team's president of basketball operations, was emotionally numb.

"As a human being, you can only process so much," he said of his emotions in that moment.

But life, like summer camp, goes on. And that's where the Warriors are as they embark on a summer with their dynasty on a knife's edge. In the days after their devastating Finals, where they lost Kevin Durant and Klay Thompson to terrible injuries, the Warriors have developed an audacious plan to try to hold their status as a championship team together, sources told ESPN.

Much of it centers on a huge volume of money. By the time free agency opens Sunday at 6 p.m. ET, the Warriors will have offered both Thompson and Durant full five-year maximum contracts. For Durant, that means $221 million, and for Thompson, $190 million. Even with the reality that Durant might miss all of next season recovering from a torn Achilles and Thompson might miss the bulk of it coming back from an ACL tear, this remains the Warriors' first choice.

For the Warriors to make max offers to both players and to retain free agent Kevon Looney, which is also a priority, their payroll this upcoming season could balloon to more than $375 million, including more than $200 million in luxury taxes, according to projections by ESPN's Bobby Marks.

This would create the most expensive team in league history, which the Warriors would be able to afford only because the brand-new Chase Center opening later this year in San Francisco is estimated to generate more than $200 million in new revenue, sources said. Within the past two years the Warriors have passed the New York Knicks and Los Angeles Lakers as the highest-earning team in the NBA, eclipsing the $400 million mark in annual revenue, according to sources.

Still hugely in demand despite his injury, Durant will get numerous other offers. If he wants to go elsewhere now, the Warriors are preparing plans to pivot and potentially try to work with Durant on a sign-and-trade deal. Myers has been staying in contact with Durant and his business partner Rich Kleiman since the season ended, according to sources.

Doing a sign and trade would enable Golden State to perhaps create a $37.6 million trade exception. This could prove remarkably valuable instantly, as the Warriors could then become players in the free-agent market. They couldn't use the exception to immediately sign a player, but they could explore sign-and-trade deals with free agents, opening a significant window for them to add to the roster.

The trade exception also could be used to acquire other players over the next year. To get a team signing Durant to do this type of deal, Golden State might have to incentivize the team with an asset like a future draft pick, a scenario the Warriors have been preparing for.

If a deal to sign and trade Durant can't be worked out, the Warriors have the option of trying to retain DeMarcus Cousins. Under the rules, the Warriors can offer Cousins a salary of only $6.8 million for next season. He could very likely earn more elsewhere, and the Warriors have long prepared to lose him.

However, if Cousins were willing to return, the Warriors could build some of their offense around him from the start of the season and feature him more, something that was impossible to do last season as he was recovering from an Achilles tear. That could be attractive to Cousins if he can't find a long-term deal and wants to continue to rebuild his value. The 2020 free-agent class is more shallow than this summer's, which might convince some players to take one-year deals.

As for Thompson, the organization remains confident it can work out a deal for him. ESPN's Adrian Wojnarowski reported that Thompson was open to meeting with the LA Clippers if a deal couldn't be worked out quickly with the Warriors.

Some outstanding issues that could force Thompson to look to create leverage involve the terms of the deal. When the Warriors locked Stephen Curry into a five-year max deal in 2017, the team didn't allow Curry an opt-out clause in the last year of the deal and also didn't give him a no-trade clause, two valued items that superstars often negotiate. That set a precedent in how the Warriors look to deal with their other stars, and those deal points could become prickly in talks with Thompson, depending on his priorities.

Also this summer, the Warriors can negotiate an extension for Draymond Green, who has one season left on his contract. Green has expressed an interest in landing a new deal with the Warriors in the past, and he is open to a new deal this summer, sources said. Talks are expected to take place later in the offseason.

As the Warriors said often during their injury misfortune during the playoffs, no one is going to feel sorry for them. With their aggressive plans over the next few weeks, they aren't feeling sorry for themselves either.

He might not be a superstar like some of the others in this class, but Al Horford's entry into the free-agent market has sent numerous teams into a tizzy trying to get his valued services. Much like three years ago, when a number of teams rushed to offer him a max contract when he decided to leave the Atlanta Hawks, Horford is in such massive demand across the league that he's very likely to get the four-year, $100 million-plus deal he's seeking by opting out of his deal in Boston.

In addition to teams such as the Dallas Mavericks and New Orleans Pelicans, who instantly emerged as possible landing spots, league sources say there are a few surprise bidders who are trying to land the veteran big man. These include the Sacramento Kings and Philadelphia 76ers.

The Kings are interested in adding a center this offseason, and there's space for them to do it even with re-signing Harrison Barnes. It would require them to move on from Willie Cauley-Stein, who wants that anyway, as his agent has asked the Kings to let him go.

They'd potentially have the room to make an aggressive offer to Horford, but they have a number of the top centers on their list, sources said. In addition to Horford, the Kings could chase Brook Lopez and Nikola Vucevic. Lopez played for coach Luke Walton with the Lakers.

Philadelphia has its own free agents to deal with, namely Tobias Harris, Jimmy Butler and JJ Redick. Maybe the 76ers re-sign their guys and are never in the market. But if they don't re-sign all of them, they will have cap space, and they could chase Horford. Philadelphia has a wide range of options and is perhaps the most intriguing team to watch this summer.

One of the best spots for a player to be in is that of the gettable restricted free agent. Players who are in this gray area, where their teams might not match any offer, can sometimes drive fantastic deals, maybe even better than they could get if they were unrestricted free agents. Two players who've fit this bill in recent years are Zach LaVine and Otto Porter Jr., both of whom were believed to be gettable, and they landed tremendous offer sheets (which were matched).

This year, the player who seems to be squarely in that zone is restricted free-agent guard Malcolm Brogdon. With the Milwaukee Bucks facing a luxury-tax bill if they re-sign Khris Middleton, as they are expected to do, teams could challenge Milwaukee with a so-called toxic offer sheet for Brogdon. League executives believe a team could construct an offer sheet with the highest salary next season and then descending payments combined with a player option and possible bonuses that the Bucks might have to pay, but a new team might not.

The Chicago Bulls, Boston Celtics (if they don't land Kemba Walker), Phoenix Suns and Mavericks could consider an offer sheet for Brogdon and test the Bucks.

Meanwhile, the Bucks have not totally closed the door on George Hill, sources said. With just $1 million of his $19 million contract guaranteed, Hill will be waived by the Bucks. But the two sides have an interest in working something out to have Hill return. He could be an option if Brogdon gets an offer elsewhere that the Bucks don't match.

The center position is deep in this free-agent class, but one player to keep an eye on is DeAndre Jordan. As Jordan is one of the league's best defenders and a close friend of Durant's, teams who have interest in Durant have interest in bringing Jordan aboard as well, including the Brooklyn Nets and Knicks, where Jordan finished last season.

But Jordan, who played nine seasons with the LA Clippers, has an interest in playing in Los Angeles again, sources said. He would potentially be a fit for the Lakers, who are expected to try to find a way to sign Jordan and play him alongside Anthony Davis and LeBron James.

The Golden State Warriors are planning to offer All-Star guard Klay Thompson a five-year, $190 million maximum contract when free agency opens Sunday at 6 p.m. ET -- which is expected to accelerate the process of general manager Bob Myers and Thompson's agent, Greg Lawrence, quickly reaching a formal agreement, league sources tell ESPN.

Thompson and Lawrence have indicated throughout the past year that the five-time All-Star guard planned to return to the Warriors if offered the full five-year max deal -- and that's on course to happen now, league sources said.

Thompson is one of the NBA's best all-around players and a foundational talent for a franchise that's won three championships and reached five NBA Finals with him as a star performer.

Despite suffering a torn ACL in his left knee in the NBA Finals, the Warriors remained committed to keeping Thompson out of free agency and bringing him into the franchise's new downtown San Francisco arena with Stephen Curry into the future.

Several teams pursuing Thompson in free agency have given up hope in recent days, believing that he was moving toward a return to the Warriors.

Now the Warriors will turn toward trying to retain All-NBA star Kevin Durant, who is entering free agency. Durant suffered a torn Achilles in the NBA Finals and could miss an entire season.

Thompson has had seven consecutive seasons with at least 200 3-pointers, tied with Curry for the most in NBA history. He has eight straight seasons of shooting at least 40% on 3-pointers, which is the league's second-longest active streak in the NBA behind Curry. His 1,798 career 3's are 16th all time.

Thompson is one of the league's elite wing defenders, too. He was a second-team All-NBA defensive selection this year.

Prior to the ACL tear, Thompson had been one of the most durable players in the NBA. He has missed only 25 games (including playoffs) since Steve Kerr arrived as coach in 2014. He's played at least 70-plus games, averaging more than 30 minutes each of the past seven seasons. Only James Harden, Damian Lillard and Thaddeus Young have had similar runs in that span.

Thompson was selected 11th overall by the Warriors in the 2011 draft. He's a five-time All-Star and two-time third-team All-NBA player averaging 19.5 points and 42% 3-point shooting in his career.

The London series between the New York Yankees and the Boston Red Sox will feature a giant mascot race with a British spin.

Winston Churchill, Freddie Mercury, King Henry VIII and the Loch Ness Monster will race around the warning track at London Stadium. The four were chosen by fans who voted on four categories of notable Brits -- cultural icons, legends, historical figures and monarchs.

Mercury beat out Shakespeare and John Lennon in the voting.

Prince Harry, the Duke of Sussex, will attend Saturday's opener and will accompany competitors from the Invictus Games onto the field to throw out the first pitch.

The Kingdom Choir, which stole the show at the Royal Wedding of Prince Harry and Meghan Markle in 2018, will perform the national anthem on Saturday.

About 1,500 invited fans attended batting practice Friday. Movie director Spike Lee walked around in foul territory, while the grounds crew performed to the Village People's "YMCA," as they are wont to do in the Bronx. Delaware North, the stadium food contractor, brought over George Raub, a 39-year-old from Georgia, to teach staff how to hawk food in the stands.

"It's all about showmanship and bringing them outside of their shell," Raub said. "Joked a little bit: If they've ever wanted to be a West End actor here in London, this is their chance to really showcase their skills."

Players from both teams relished being able to do some sightseeing around the city without being recognized.

Yankees slugger Aaron Judge said he walked near the London Eye and reliever Chad Green toured the Churchill War Rooms under the streets of Westminster. Boston outfielder Mookie Betts played golf and ate with his family at Borough Market, while Rick Porcello and Red Sox teammate Brandon Workman went to Camden Market, Shoreditch and Piccadilly Circus.

"I was actually walking near the London Eye yesterday, and I ran into a couple people that had the Yankee hat on," Judge said. "They had no idea who I was or anything. I said this is all right. 'I'm Aaron, great to meet you.'"

Boston manager Alex Cora and Yankees counterpart Aaron Boone went to Buckingham Palace for the changing of the guard, and Cora visited Kensington Palace. A gala was scheduled for the Tower of London.

The Associated Press contributed to this report.

SANTO DOMINGO, Dominican Republic -- Authorities in the Dominican Republic say they have arrested the mastermind behind the shooting of baseball great David Ortiz earlier this month in an apparent case of mistaken identity.

Police said Friday that Victor Hugo Gomez was detained in the Caribbean country. No further details were immediately released.

Authorities had said last week that they believed Gomez was living in the United States.

He is accused of ordering the killing of his cousin, Sixto David Fernandez. Authorities say hit men confused Ortiz with Fernandez during the June 9 shooting at a bar in the capital of Santo Domingo. The two men are friends and were sharing a table.

Ortiz was flown to Boston and remains hospitalized there after doctors in the Dominican Republic removed his gallbladder and part of his intestine.

CHICAGO -- A potential final piece to the Chicago Cubs' bullpen made it back to the majors Thursday, as the team called up new closer Craig Kimbrel, who earned the save in a 9-7 victory over the Atlanta Braves.

After Kimbrel made four appearances at Triple-A Iowa, the organization is hopeful he'll help the team improve on its 60% save-conversion rate. Here are some key questions about the man some might think is the savior for Chicago's shaky bullpen:

The Cubs are 39-3 when leading after eight innings. Does Kimbrel make that big of a difference?

He does, but it has only a little to do with the ninth inning. The team has been short an arm since the winter, so adding a good one -- in any role -- was a top priority. Of course, it doesn't hurt to add a Hall of Fame-caliber closer, considering the ninth inning can be a different animal, but the biggest benefit could come before the ninth. That's when Pedro Strop will pitch once again, and before that, tough righties Steve Cishek and Brandon Kintzler will see action. The Cubs have blown seven leads in the seventh inning or later, so moving everyone down a notch is where Kimbrel truly helps.

"When everyone is [available] on a nightly basis, the length of the bullpen gets pretty deep," Cubs manager Joe Maddon said.

How will Kimbrel be used initially?

First off, he'll pitch only three or fewer outs. So one inning will be the right-hander's max. "Remember when I got Aroldis [Chapman] and popped him in there for three-plus [outs] and I thought it was cool?" Maddon said. "But it wasn't."

"He'll be slotted, and really carefully. As we get to the latter part of September, as it's necessary, that's where you look at the four outs sometimes. I hope not five. ... He'll be a three-out guy."

What about using him on back-to-back days?

Kimbrel pitched on back-to-back days one time last week at Triple-A, so he's prepped for it. It'll be a day-by-day thing between him and Maddon.

"I need him to tell me on a daily basis how he's feeling," Maddon said. "I will listen to him. ... Sometimes, these guys actually feel better after a couple days of pitching."

Is he in major league-ready shape?

Kimbrel was throwing at a local high school in Florida before being signed, so it's not like he was mimicking big league situations -- hence the time in the minors. The Cubs called it his spring training and will treat him accordingly.

"Guys have a few more restrictions in April because they're easing their way into the season a little bit," team president Theo Epstein said. "It wouldn't be appropriate to go full throttle right off the bat given the long season ahead of him. And given that they are just getting up to speed.

"It makes sense to look at it like April, where you're not going to push the pedal to the metal right away, and be smart about it."

What are scouts or other executives saying?

One assistant general manager of another team interested in Kimbrel saw him throw before the 31-year-old signed with the Cubs and said: "I'm curious to see how the next few years play out. Our scout said the velocity looked good, command was off. Even then, it's hard to put any stock into it."

A scout who saw him more recently, at Triple-A, said: "Velocity was good, and in the few batters I saw, no one squared him up. But the real test is coming. This was just to see how his arm looked, and it was fine."

How did he look Thursday?

Kimbrel hit 95-98 mph on the radar gun but lost command against Dansby Swanson, walking him on four pitches.

"His stuff is still electric," new teammate Cishek said. "He had, what? Seven or eight strikes in a row. That's pretty amazing in his first game."

So how did his signature setup on the mound -- with his right arm dangling -- come to be?

"It all started with an injury," Kimbrel said. "I didn't want to put my arm behind my back anymore. Started to let it hang because I was getting a little bicep tendinitis. Over the years, it got out of control. It became something that was more of a stamp in my performance, I guess. Now it's just something that I do. It's how I separate from a happy, fun-loving guy to turning into what I want to be on the mound."

Scot makes his comeback after injury at the British Milers’ Club meeting

A line-up of top British 800m runners will be on show for the third BMC Grand Prix of the season, which takes place at the Woodside Stadium in Watford on Saturday.

Jake Wightman will be racing for the first time since suffering a stress fracture to his sacrum in December, while Alex Bell – who broke the two-minute barrier at last year’s meeting – also makes her first serious appearance of the outdoor track season.

Wightman was the fastest British 800m runner last year after setting a PB of 1:44.61 at the IAAF Diamond League meeting in London and he will be joined on the start line by Elliot Giles (1:44.99), as well as last year’s Commonwealth silver medallist Kyle Langford.

All will be wary of Rio Olympian 1500m runner Charlie Da’Vall Grice, who opened his season in America earlier this month with a 1:46.47 800m and a 3:54.77 victory over the mile. Spencer Thomas and Jamie Webb are also entered.

In the women’s race, Bell can expect stiff opposition from European Indoor champion Shelayna Oskan-Clarke, Sarah McDonald and Revee Walcott-Nolan, while Glasgow 2019 fifth-placer Mari Smith will also feature.

“I think we are looking at one of the finest fields of British 800m runners we have had for many years,” said BMC chairman Tim Brennan.

“We could easily be looking at a 1:45 time to win the men’s A race as we have two guys who ran 1:44 last year.

“We also have Alexandra Bell coming back to the track where she ran sub-two (1:59.93) for the first time when winning last year . Both A races are shaping up to be very exciting.”

The meeting is much more than just about the 800m, however. Rio Olympian Andrew Butchart joins a men’s 1500m field which also features the likes of Ellis Cross and Phil Sesemann while Jess Judd, who has won the 5000m at the opening two Grand Prix, will step down to the women’s 1500m and is joined by Hannah England.

Entries for the two steeplechase races headed by Zak Seddon and Elizabeth Bird, while some of Britain’s top junior distance runners will also be in Watford as the UK under-20 3000m trials are being incorporated into the meeting.

Morpeth’s Rory Leonard has already made a big impact over 5000m this summer so will be stepping down for some sharpening up work, while Cornwall AC’s Grace Brock heads a good entry for the women’s race.

The first race is at 5.30pm.