Twice in a two-year span, Dallas Mavericks assistant coach Greg St. Jean lived in near isolation with an NBA superstar.

First in the NBA’s infamous COVID-19 bubble, where then-Lakers assistant St. Jean bonded with LeBron James as Los Angeles’ staff helped him lead an unprecedented championship run in Disney World.

Two summers later in a less strict but more eye-opening Slovenian hotel bubble, where Luka Doncic and his national team invited St. Jean to experience two weeks of EuroBasket prep and to deepen his relationship with the Mavericks’ 23-year-old star.

That makes St. Jean an expert on at least two things:

Basketball-focused solitude, and understanding how relationships with James have influenced the Mavericks’ approach with Doncic.

When James and the Lakers visit Dallas this weekend for the first Christmas Day showcase at American Airlines Center in over a decade, the LeBron-Luka connections — a generational icon and one rising to that level who admired James growing up — will be apparent.

St. Jean has connected with Doncic over the last six months through tough-love basketball, competitive humor and Slovenian immersion, showing the overlap is more intricate than just Doncic and James’ mutual public appreciation.

“LeBron’s biggest thing is respect, and any of the great players, they want to be coached,” St. Jean said. “That’s kind of been Luka’s and I’s relationship, too. We’ve seen some high-stakes moments together where we’ve built a trust together that I’m not always going to be right, but more times than not, he believes in me, and I always believe in him.”

St. Jean, a Lakers player development coach before moving from Los Angeles with Mavericks coach Jason Kidd in 2021, spent most of the three-month 2020 NBA bubble stay in constant communication with James.

James wanted to dissect every detail, every coverage option, every action, every manipulation to gain an edge in every game. At night, St. Jean would send texts to James with video clips, asking questions about his vision on each play.

“If you can help LeBron be prepared to be great,” St. Jean said, “he’s going to always respond well to that.”

Kidd, the Lakers’ lead assistant from 2019-2021, remembered that connection when he needed to reshuffle responsibilities this season after former Mavericks offensive coordinator Igor Kokoskov’s departure.

Kokoskov worked closely with Doncic in his coaching “pod,” which is how Kidd divides the roster among assistants to ensure individual and direct attention for workouts, development and communication.

Kidd said the mutual respect between St. Jean and James made him think the assistant could forge a similar relationship with Doncic.

“I thought it would be a great match,” Kidd said with a laugh, “and it’s turned out to be a great match.”

Thanks, in part, to St. Jean spending two weeks in early August in Doncic’s native Ljubljana to better understand his culture.

He ate Slovenian food, toured some of the city to see the best hiking and winter sports areas, and witnessed how much pride the Balkan country of two million people felt toward its loyal NBA superstar

. Jean also learned why playing for the Slovenian national team has been so important to Doncic every NBA offseason.

While preparing in early August for a pair of World Cup qualifiers and the prestigious EuroBasket tournament, the national team ate every meal together — breakfast, lunch, dinner and snacks. They practiced as a full team every day. They coordinated outfits. They played a lot of ping-pong and poker.

St. Jean joined it all.

St. Jean learned Slovenian phrases like dobro (good), lepa (beautiful) and pojdimo (let’s go), and he has worn his Slovenia gear during Mavericks road trips. He and Marko Milic, head of the national team and a new Mavericks assistant this year, have an ongoing bet during Doncic’s pregame warm-ups — push-ups for half-court shots.

On the Slovenian team, players keep a tab of push-ups and can call out anyone in debt at any time — even, as St. Jean saw, in the middle of a mall.

When Doncic misses all three of his half-court attempts before a game this year, he has to pay up in front of scores of fans. More often, St. Jean and Milic drop down as Doncic laughs and pumps his fists after a swish.

That’s the closest he’s been to winning an NBA championship. He got a taste of it, and he got to see the intensity level it takes to win a series and win a Game 7 and go and get a chance to play against the champs. He’s not going to be the one to tell anybody verbally, but as an elite competitor, he didn’t sit there and go home and say ‘I’m satisfied.’

“Those guys that have the elite 1% work ethic, elite 1% talent, elite 1% drive, they hit a moment where they just take off, and I think we’re seeing Luka touch that.”