Well before the coronavirus pandemic halted sports in the United States in March, Top Rank had to make a decision. On Jan. 23, unified junior welterweight titleholder Jose Ramirez was preparing to fly to Haikou, China, to face Viktor Postol. A call came: Stay home. The fight was off.

A similar call went to Postol, who had landed with his team in China earlier that day. Get back on a plane. The illness sweeping through Wuhan was spreading.

That was the first of many cancellations in sports worldwide. From March until June, boxing has essentially been shut down.

The return of boxing to the United States has taken months of planning. The study of over 20 different protocols from sports leagues to movie studios to large corporations led to the creation of a 20-page, five-pronged plan, which Top Rank delivered to the Nevada State Athletic Commission to make Tuesday's fight card headlined by Shakur Stevenson vs. Felix Caraballo happen in Las Vegas.

"I've been in this business way longer than I want to admit," says Brad Jacobs, Top Rank COO. "And this has been, by far, the most difficult process I've been through."

Tuesday's card -- and the rest of Top Rank's cards for the foreseeable future -- will look and feel different than any other fight night. Instead of an arena, the fights will take place in a studio setting that looks almost like a concert setup inside a room at the MGM Grand Conference Center. The center is part of the bubble MGM and Top Rank set up to quarantine and keep their fighters safe. There will be no fans. Limited media, including ESPN's Bernardo Osuna, will be on-site. Polymerase chain reaction (PCR) testing, which helps detect COVID-19, will be commonplace.

"Everyone understands we're living in a different world here and [testing positive is] part of what potentially could happen," Jacobs says.

"Potentially" became reality, as the system Top Rank put in place showed its efficacy Sunday, when co-feature fighter Mikaela Mayer was pulled from the card after a positive COVID-19 test.

But the card goes on. The fighting will be familiar, but the events will operate differently. Fewer fights a night, a reduction in cornermen and assigned cutmen, adjustments made to reintroduce boxing to the world in the sport's home, Las Vegas.

From the start, Top Rank president Todd duBoef wanted boxing's return to be in Vegas, though he wasn't always sure it would happen.

In the days following the postponement of Stevenson's March 14 fight in New York and before the country realized how long the pandemic would last, duBoef reached out to MGM to see if he could put on fan-less shows at its Vegas facility. He also checked in with UFC president Dana White to see if the Apex would be available.

Soon after, duBoef's thoughts were scuttled. Borders closed. Commissions shut down. Boxing needed, like the rest of the sporting world, to pause. But Vegas remained duBoef's hope. The Nevada State Athletic Commission would have to allow for events to take place.

"It was a little bit of a selfish interest from all of us that seeing the city and the state decimated the way it was, it was like, if we were going to bring back some business or start to show the world, reintroducing sports back into the world on television, we felt it was important because Nevada was our home state," duBoef says. "They needed to be at the center or working with us, the consumer or average person, 'Hey, let's get some confidence back. Las Vegas is still around.'"

This isn't to say they didn't consider other places. Jacobs spoke with at least 20 other venues across the United States as options. But Vegas was the goal. Everywhere else was Plan B or C.

While Top Rank waited for a venue, Jacobs studied. After the initial shock of COVID-19 set in, he created a file in Evernote and carried it with him everywhere he went. It was his constant reference tool, as he began contemplating what a return-to-fight protocol might look like.

If he saw something in another protocol he liked, he jotted it into his Evernote file. Headings such as Testing, Venue, Training Center, Sanitizing Vehicles and Personal Protection Equipment (PPE) all took up space.

By April 1, Jacobs put together the first of at least eight iterations of the Top Rank playbook for returning to fights. It began with broad ideas. As he researched, the plan became more detailed.

The latest version, obtained by ESPN, begins with a five-pronged approach: establishing an internal task force; reviewing and identifying any potential exposure risks; establishing a method of emergency communication; creating the safest possible environment to protect everyone; and executing the plan.

Before fighters arrived in Las Vegas for the final stages of camp -- after sparring completed -- they filled out a questionnaire asking if they had come into contact with anyone with COVID-19, if they've had a fever at or above 99.5 degrees Fahrenheit in the past 72 hours, what their recent travel history was and whether they had any symptoms before they drove or flew to Las Vegas. While fighters and their teams were encouraged to drive, flying was allowed.

While the time frame was different for the first card because MGM did not reopen until June 6, main event fighters will typically arrive the Friday before a Tuesday card or the Sunday before a Thursday card. The rest of the fighters will show the following day.

Once fighters land in Vegas, teams are transported in a sanitized vehicle to take a PCR test, the results of which will take six hours. If a fighter or anyone on their team tests positive either at this test or at the test following the weigh-in, he or she is immediately quarantined, and the fight is off. For the first few fights, duBoef said, they don't have backup fighters -- but as they start to build cards, there might be some flexibility to move fights or fighters around at the last minute. If tests are negative, the team will be allowed to check in to the MGM Grand Hotel at a private entrance.

They'll be taken up a back elevator to a designated floor in the hotel for Top Rank. No access will be granted by elevators for other hotel guests, and all movement to and from the floor will come from a back-of-house elevator.

When the fighter arrives, he or she will be given a bucket, water bottle and jump rope with their name on it to use for the duration of their stay. Upon departure, they can either take the equipment with them or have it discarded.

A training schedule at a gym set up in the conference center will be provided -- as well as transportation in a sanitized vehicle from the elevator to the convention center. While the gym will be cleaned daily, it is the responsibility of the fighter and his or her team to clean and sanitize after themselves.

Everything will be done in the convention center bubble: meals, training and the fights themselves. Access to the bubble will be allowed only for those who have a dated and color-coded wristband allowing entry. If anyone leaves the bubble, they have to take another COVID-19 test to reenter. Masks will be worn at all times except when eating and in hotel rooms.

"Their initial operation plan was very creative, comprehensive and addressed all the issues," says Bob Bennett, the executive director of the Nevada State Athletic Commission.

Bennett and Jacobs were in touch often in the planning process, including using the five-page NSAC protocol as a guide. The Top Rank plan already had many of the requirements in place from the NSAC document, including the establishment of a closed system -- or bubble -- for the safety of all involved. The NSAC document also called for the pre-travel questionnaire and temperature checks along with the PCR testing upon arrival. It also addressed the necessity of contact tracing if a positive test occurs (at the expense of the promoter) and a 14-day quarantine for any fighters testing positive, including no air travel.

"To have a closed system," Bennett says, "which means it's coordinated, everybody's accountable that comes in or out of our system."

The trip for Bernardo Osuna will be an easy drive from Orange County, California, to Vegas. When he arrives, it won't be the same. The ESPN announcer will be under the same protocol as everyone else: Arrive. Test. Quarantine. Work.

He'll also be alone. The rest of his usual team calling the fight for ESPN -- play-by-play man Joe Tessitore and analysts Mark Kriegel, Andre Ward and Tim Bradley -- will be remote, each in their own separate location. A remote broadcast app will be set up in Osuna's hotel room to allow for live TV segments. The crew has gone through preparatory runs, but Bradley knows it will be different because he won't be able to see some of the things he catches live. He'll miss hearing the punches.

Instead, Bradley will be watching the monitor inside his home office, with his 20-year-old son, Robert, as his emergency IT guru. The rest of his family, because voices carry in his home, are expected to leave for San Diego for the week on Tuesday morning.

He'll have an iPad hanging above an open laptop as his dual visual apparatus, with the iPad showing him the feed of the fight and a Zoom call with Tessitore on the laptop so he can at least see his broadcast partner. The hope is his longtime work with Tessitore will make any potential talking-over-each-other issues easier to navigate.

"The main thing I really worry about, honestly, is the connection," Bradley says. "What happens if my internet dies just for a second? Sometimes it happens, man. You get a shortage in your internet for a split second and it's like, 'Where's Tim Bradley? Oh, I lost Tim Bradley.' Now I got to find my way back home."

If there is a technical glitch, Osuna is on-site, though he's there to be a reporter. Osuna will try to get information from corners during rounds and talk with trainers -- from 6 feet away. With it likely being quieter in the studio, Osuna is concerned some trainers might not be as willing to share information at risk of being overheard, but he's hopeful.

He'll also be doing interviews with a fish pole boom mic to make sure social distancing remains in play.

"The whole reason I will be in Vegas is because I will provide those eyes and ears," Osuna says.

Mayer just wanted to fight. She had finished a long camp preparing to face Melissa Hernandez on March 17 when COVID-19 emerged and shut down her fight. Mayer traveled back to Colorado, and once she realized she wouldn't be fighting anytime soon, Mayer secluded herself on a weeklong camping trip with her two best friends.

Then, she came home, put up an Everlast heavy bag and tried to stay in shape. She cleared out her house to learn how to inline skate -- a one-day experiment shut down remotely by one of her coaches, Al Mitchell. This worked for a couple of weeks, but motivation waned, so she packed up her Jeep with her dogs, Luna and Moose, some belongings and her best friend and fellow boxer, Ginny Fuchs, for a 20-hour drive from Colorado to Washington, D.C., to start training and quarantining with her other coach, Kay Koroma.

"We didn't even have the lights on in the gym," Mayer says. "There was no electricity running while there was quarantine, they shut that all off, but we had it opened up for us. Coach Kay had a friend there who opened it up for us, and we would bring one or two people in for sparring while we were there.

"It was just us, four or five people in the gym."

Those surroundings changed in mid-May as soon as Koroma moved camp from Washington, D.C., to Houston's Main Street Boxing. Fuchs and Mayer packed up the Jeep again and drove to Texas -- doing what they could to stay away from people despite traversing the country in preparation for a fight. With relaxed social restrictions in Texas implemented soon after she arrived, gyms were opened up.

After all that time isolated, Mayer was now in a crowd.

"[It was] super weird and a little nerve-wracking because all of a sudden the gym is packed with younger people, and I'm like, 'How safe are these young people being before they come into this gym?' Even though I wasn't quarantined at home like a lot of people were, locked in their house ... I was very cautious."

Mayer needed the sparring work ahead of her bout against Helen Joseph, so she continued to train and understood the risks. She took precautions not only for herself, but as a way to look out for her coaches. She says she consistently washed her hands after touching public surfaces, used hand sanitizer and avoided touching her face.

"Boxing is really the only thing I'm willing to risk my life for. Like, the career that I've built for boxing is worth my life," she says. "So this is my livelihood. I wasn't going out to go out and hang out at peoples' houses or doing anything like that. That's not worth it to me.

"Being in the gym and training for a fight, that's worth it. So I had to do what I had to do."

Mayer left Houston for Las Vegas late last week and took the only plane ride of her journey over the past three months. She entered the "bubble," then isolated as she awaited her results. On Saturday she was asymptomatic, but positive.

It's not clear where she contracted COVID-19, but regardless, she was ruled out. Instead of quarantining in Vegas, she decided to drive solo back to Colorado to recover. Both Mayer and Top Rank hope to get her back in the ring later this summer if she tests negative for COVID-19.

"After two hard back-to-back camps, not being able to step [into] the ring both times, you can imagine how disappointed I am," Mayer wrote on Instagram. "However, these protocols were put into place for a reason and it's more important to care about the health and well being of my team and the people at this event."

With no alternates available for this card, Joseph was left without an opponent and, just like Mayer, will have to wait to get back into action. Top Rank shifted another fight, Jared Anderson vs. Johnnie Langston, into the "co-main" spot, fired up its marketing efforts and refocused on executing Night 1.

Top Rank also had to work with Stevenson and Anderson on Monday to find a new cornerman after Koroma was removed from the bubble due to his contact with Mayer since arriving in Vegas. Koroma was scheduled to corner both men in their respective fights.

That sort of flexibility is going to be the key. Top Rank can put all its plans in place, safeguard its fighters and its staff as much as possible and hope everything goes right -- until it doesn't.

Jacobs said they'll evolve as they learn. He knows things change fast. Right now, the biggest concern is safety -- and getting a good first show off. Everything else can be tweaked later.

"Healthy and safe is the No. 1 priority," Jacobs says. "After that, having great fights that are entertaining and [for] a person sitting at home, watching the fights with a smile on their face, we succeeded."

They recognize it's a chance to bring the sport to a new audience, too, as Top Rank will be the only live sporting event on Tuesday and Thursday nights for the time being. In Las Vegas.