There aren't many days that go by during the NBA season when LeBron James doesn't use lessons he learned during his four years with the Miami Heat.

One has proven to be the most important: Keep the main thing the main thing.

It is one of the core tenets that Heat president Pat Riley has preached for years, and it's one that James holds dear. Even with his growing media company, his charity work in his hometown of Akron, Ohio, his activism and his love of fine wine, James never lets himself forget the main thing: chasing championships.

The main thing is here: Heat vs. Lakers in the NBA Finals.

The Riley-James dynamic, which essentially is the Heat-James dynamic, is complex.

James has two rings with Heat logos, he accepted two MVP trophies at AmericanAirlines Arena, and he probably will have No. 6 retired by the franchise someday. He credits Riley and the Heat not only for teaching him to become a champion but also for helping shape his world view.

Yet when they broke up in 2014, Riley was furious, and James was offended. Although James felt a pull to go home to Cleveland more than he felt a desire to leave Miami, there wasn't much room for nuance.

"I saw a dynasty fly out the window," Riley told ESPN four years later. "I knew that was a 10-year team. I wanted that dynasty."

James was turned off by the attitude the Heat took when he left and by something that was said to him.

"When I decided to leave Miami ... there were some people that I trusted and built relationships with in those four years [who] told me I was making the biggest mistake of my career," James said the night he won a title with the Cavs in 2016. "And that right there was my motivation."

James never said who it was, though many assumed it was Riley. They had an acrimonious phone call shortly before he made his announcement. Riley denied saying it. Either way, Riley took a major swipe at James several months after he left when he said the team had rid itself of players who had "smiling faces with hidden agendas."

They didn't communicate for years until Riley sent James a text the night of the 2016 title. James did not reply.

The truth is the philosophies of the Heat and of James ran so very close then and now. They are both obsessed with the nature of winning, a process that unfolds every day of every season, in which glory is earned just as much in the mundane discipline of routine as in the arena.

Both operate with a militaristic ethos, in which teammates are considered a band of brothers and are to be held to extreme accountability. Both believe in a family culture but have no problem casting aside a piece or two if it improves the chances of winning.

They are so much alike that perhaps they were never meant to stay together.

In nine playoff runs with the Cavs, James never met the Heat. In his first playoff run with Los Angeles, he will play his old team for the first time with the highest stakes.

Revenge isn't really covered in the "main thing" doctrine in these Finals. James is playing for legacy and in honor of Kobe Bryant. The Heat are trying to show that their culture wins over all and show off as a drawing card for free agents in the future.

But revenge won't be that far from the surface, either.

-- Brian Windhorst

Series schedule

Game 1, Sept. 30: Heat at Lakers | 9 p.m. ET on ABC
Game 2, Oct. 2: Heat at Lakers | 9 p.m. ET on ABC
Game 3, Oct. 4: Lakers at Heat | 7:30 p.m. ET on ABC
Game 4, Oct. 6: Lakers at Heat | 9 p.m. ET on ABC
Game 5 (if necessary), Oct. 9: Heat at Lakers | 9 p.m. ET on ABC
Game 6 (if necessary), Oct. 11: Lakers at Heat | 7:30 p.m. ET on ABC
Game 7 (if necessary), Oct. 13: Heat at Lakers | 9 p.m. ET on ABC

Lakers' road to the Finals

The basics

• 2019-20 record: 52-19 overall

• Offensive rating: 111.7 (11th) | Playoffs: 115.6 (second)

• Defensive rating: 106.1 (third) | Playoffs: 107.8 (fifth)

Playoff results

• Round 1: Def. Portland Trail Blazers 4-1

• Round 2: Def. Houston Rockets 4-1

• Round 3: Def. Denver Nuggets 4-1

To take some liberties with Moses Malone's famous prophecy, the Lakers went "fi', fi' and fi'" through the first three rounds of the playoffs.

After dropping Game 1 of the first round against the Trail Blazers, L.A. won four straight after bubble MVP Damian Lillard left the series early because of a right knee injury. The conference semifinals followed a similar script: The Rockets won Game 1, and then the Lakers finished them off by winning four straight, changing up their defensive schemes on James Harden to keep the league's leading scorer off-balance.

Then came the Denver Nuggets, the darlings of the 2020 playoffs, who came into the Western Conference showdown with Los Angeles having become the only team in NBA history to come back from down 3-1 twice in one postseason. Although the series lasted only five games, it took an Anthony Davis buzzer-beating 3 to win Game 2 and a LeBron James performance for the ages to close out Game 5 and put a determined Denver team to bed.

Dwight Howard was L.A.'s breakout role player against the Nuggets, taking over for JaVale McGee with the first unit at halftime of Game 3 and keeping that starting center spot the next two games. He averaged 10.5 points on 80% shooting, 10 rebounds and 1 block to close things out. He finds himself back in the Finals for the first time since 2009, playing in the city he took there, Orlando, Florida, and seeking a ring to validate an otherwise Hall of Fame career.

"I promised myself if I ever got a chance to get back, I was going to give everything I got to help our team win," Howard said. "I didn't think this would ever happen, but I'm just so thankful and grateful that I have this opportunity, and I'm going to make the most of it."

-- Dave McMenamin

Heat's road to the Finals

The basics

• 2019-20 record: 44-29 overall

• Offensive rating: 111.9 (seventh) | Playoffs: 112.7 (fourth)

• Defensive rating: 109.3 (12th) | Playoffs: 108.6 (seventh)

Playoff results

• Round 1: Def. Indiana Pacers 4-0

• Round 2: Def. Milwaukee Bucks 4-1

• Round 3: Def. Boston Celtics 4-2

The Heat have been dominant in the postseason, with a sweep of the Pacers in the quarterfinals, a five-game win over the No. 1-seeded Bucks in the semifinals and an impressive, six-game triumph over the Celtics in the Eastern Conference finals. As usual, it was a balanced attack that lifted Miami to the Finals, led by All-Star Jimmy Butler, who has had help up and down the roster.

Bam Adebayo has shown why he was an All-Star. Veteran guard Goran Dragic has been great for the Heat and will be a focus of the Lakers' defense. Rookie Tyler Herro isn't going to be afraid of the moment and has the ability to go off the way he did in Game 4 against Boston.

Miami's defense has been on point throughout the bubble -- the Heat succeeded in mixing in zone during the East finals -- but was especially so down the stretch against the Celtics. When the Heat needed to turn the game around, it was their defense that delivered, a trend set by Adebayo's game-saving block on Jayson Tatum at the end of Game 1.

-- Nick Friedell

Series key: Rebound battle could help decide the Finals

Back when Pat Riley was stalking the sideline for these two franchises, the Heat president popularized the phrase "No rebounds, no rings." Although offensive rebounding has been diminished in the NBA since Riley's heyday, it remains important to both of these teams, making that a matchup to watch during the Finals.

So far in the postseason, the Lakers and Heat are No. 1 and No. 4, respectively, in points per miss, according to Cleaning the Glass. The Lakers aren't just leading the field; they're lapping it. Their average miss has generated .23 points, farther ahead of second-place Dallas (.19) than the Mavericks are from league average (.16).

This is nothing new for the Lakers, who ranked third in points per miss during the regular season. The Lakers have typically started two traditional big men capable of wreaking havoc on the glass in Anthony Davis and JaVale McGee or Dwight Howard. Howard and McGee rank fourth and fifth respectively among postseason regulars in offensive rebound percentage.

By contrast, the Heat's offensive rebounding prowess is more surprising. They had the league's third-lowest rate of points per miss during the regular season. Miami has gotten timely offensive boards from small forward Butler, who has grabbed 7% of available offensive rebounds in the playoffs, a rate better than that of the average power forward. The Heat's relentless energy has also produced second chances that haven't been credited to players as offensive boards, as noted by Seth Partnow of The Athletic.

The Lakers are better equipped to control the defensive glass than the Heat. They've also been among the league's top defensive rebounding teams this season and won't be as vulnerable when they go small as the Celtics were during the conference finals because they keep Davis at center. But we'll see if Miami can continue hustling its way to second chances in this series.

-- Kevin Pelton

Series key: Anthony Davis vs. Bam Adebayo

Anthony Davis dominated his West playoff opponents, averaging 28.8 points on 57.1% shooting through 15 games. But in the Finals, he will face his toughest matchup to date in Miami's Bam Adebayo. Unlike the bigger but slower bigs on the Nuggets and Trail Blazers or the undersized bigs of the Rockets, Adebayo has the combination of length, girth and quickness to slow down Davis one-on-one anywhere on the court.

Per Second Spectrum, Adebayo gave up only 0.769 points per direct isolation during the regular season (third in NBA among players defending at least 100 isolation plays).

Both bigs do a lot of their damage on drives to the rim. According to Second Spectrum, Adebayo ranks third in in the NBA, with 1.168 points per direct drive, and Davis ranks fourth, with 1.151. On defense, Adebayo has been a bit better at defending the drive, giving up only 0.826 points per direct drive (12th in the NBA among players who defended at least 100 direct drives), and Davis gives up 0.928 (66th in the NBA).

Adebayo has also averaged 11.2 rebounds in the playoffs, fifth in the NBA but best among remaining players. Davis gets a bit more help on the glass from teammates, but his 9.3 rebounds per game in the playoffs ranks him 14th in the league.

The Lakers are led by LeBron James, who looks to make history by earning a Finals MVP with a third team while securing the franchise its 17th championship to tie the Celtics for most in NBA history. For the Heat to have a chance to earn their parade, they will need Adebayo to take on yet another superstar and play him to a standstill. He did it successfully against two-time MVP Giannis Antetokounmpo. How much can Bam limit the Brow?

-- André Snellings

Series key: Miami's troubling second halves

Depending on how much weight you put on the previous matchups between the Heat and Lakers -- L.A. victories on Nov. 8 and Dec. 13 -- the third quarters were pretty big turning points each time, with the Lakers going on runs that helped them prevail.

Los Angeles outscored Miami by 10 in the third quarter of the first matchup. Then the Lakers were a plus-11 in the third quarter of their second meeting.

Although one could argue that those were isolated scenarios, they fit what we've seen, both during the regular season and throughout the playoffs: Miami is a superior first-half club that tends to struggle after the break.

The Heat routinely got out to good starts and led the NBA in net rating in first quarters, outscoring foes by almost 13 points per 100 possessions in the regular season. But they were underwater in the third and fourth quarters, when the Heat ranked 19th (minus-1.2) and 28th (minus-5.8), respectively, in net rating.

In the playoffs, the Lakers have beaten opponents by 5.9 points per 100 possessions in third periods, and Miami has been outscored by 3.4.

Beyond that, the Heat have lost 18 games in which they held a lead of 10 or more, the most in the NBA (including regular season and playoffs). One of those losses came against the Lakers, who came back to win a game in which they trailed by 14 points at one juncture.

Miami probably will hold its own against L.A. But head coach Erik Spoelstra & Co. will need to be ready with adjustments after halftime.

-- Chris Herring