Celtics star Jayson Tatum rooted for the Lakers when he was a youngster, now he wants to beat them

Jayson Tatum is hoping to lead the struggling Celtics to a win over the Lakers Friday night.Kevin C. Cox/Getty

On Dec. 4, 2009, Celtics forward Jayson Tatum was at an Applebee’s with his cousin and watching the Lakers play the Heat on television.

Tatum’s favorite player was Lakers star Kobe Bryant, and his cousin’s favorite player was Heat star Dwyane Wade. So when Bryant rose and drilled a buzzer-beating game-winner that would become one of the iconic moments of his historic career, Tatum raced around the restaurant screaming in delight.

This offseason, Tatum was asked to take part in a promotional video for the NBA’s 75th anniversary in which he would don Bryant’s No. 24 Los Angeles jersey and recreate the memorable play.

“I used to dream about this,” Tatum said in a behind-the-scenes video from the day of the shoot.

It was nice for Tatum, but the image of him wearing the jersey of one of Boston’s most hated rivals was enough to make some Celtics fans lose their lunch. For Tatum, though, the opportunity went beyond the rivalry.

“I felt like a kid putting that jersey on,” he said Wednesday night, “because obviously the late, great Kobe Bryant, that was my favorite player. Obviously, everyone knows I loved the Lakers back then. Not the case now, but I kind of felt like a kid in that moment, because that’s what I used to do. I used to wear that jersey and run around the house and try to be like him. So, I felt like a kid again when I did that.”

On Friday night, of course, Tatum will be back in Celtics green when the Lakers invade TD Garden. And in this situation, he would certainly like to pummel his opponent.

“I think that game is special,” Tatum said. “Obviously, everyone knows the history between the two franchises. And I’ve been fortunate enough to be a part of that going on five years now. And I obviously understand who they have on their team, and especially in somebody like LeBron [James] that is one of the best to play this game. So obviously as a kid those are the matchups that you dreamed about and you don’t take for granted when you get the opportunity.”

Meetings between these two teams always generate plenty of buzz, but this one figures to be at least slightly muted because both are still trying to find their way.

Boston (7-8) slipped back below .500 with its loss to the Hawks on Wednesday night and is in a tie for ninth in the Eastern Conference. The Lakers, who are 8-8, have been similarly mediocre.

But both teams are hopeful they will soon get much-needed reinforcements. Jaylen Brown has missed the last six games for the Celtics because of a strained hamstring but is pushing toward a return, and center Robert Williams sat out Wednesday’s game because of left knee pain but is not expected to be out for long.

James, meanwhile, could possibly return Friday after being sidelined for more than two weeks because of an abdominal strain. The Lakers are just 4-6 without James this season and 4-2 with him in the lineup. Although the sample size remains quite small, the 36-year-old’s production has dipped slightly so far this season. He is averaging 24.8 points per game on 46.7 percent shooting, his lowest marks in both categories since his rookie season.

Much like the Celtics, the Lakers are still trying to build chemistry after making significant offseason changes. The team added veterans such as Russell Westbrook, Carmelo Anthony, Dwight Howard, DeAndre Jordan and former Celtic Avery Bradley.

Los Angeles has been outscored by 2.8 points per 100 possessions, the 23rd worst net rating in the league, so its .500 record might be deceiving. But any evaluation of the team’s progress would be premature until James is able to rejoin it for an extended time.

The Celtics have their own issues as they seek ways to give their 23rd-ranked offense a jolt. Tatum may have snapped out of his slump with his 34-point performance on Wednesday, but defenses will continue to swarm him and he will need assistance.

“We just have to knock [shots] down and help him out,” coach Ime Udoka said. “So if we don’t, teams are going to dare us to beat them, and you’ve just got to be confident and aggressive. Guys are working every day at it and we’ve got quality shooters. Just got to show it now.”