BOSTON — Even in the wildest of all NBA rivalries, this had to be a first: The Boston Celtics and Los Angeles Lakers split a day-night doubleheader.

The Celtics won the opener at 3 p.m. Thursday, when the trading deadline passed and Anthony Davis remained a member of the New Orleans Pelicans. The Lakers gained a measure of revenge in a thriller, 129-128 on Rajon Rondo’s buzzer-beater.

Earlier in the day, Danny Ainge scored a victory over Klutch Sports, the agency that represents LeBron James and Anthony Davis. That one is a marathon, not a two-hour clash, so the final outcome is yet to be determined, but at the very least Ainge was granted time in his dogged and worthwhile pursuit of Davis.

We might never know what impact whatever it was that Ainge said to the Pelicans had in keeping them from panicking and sending Davis to the Lakers, but we do know it certainly didn’t hurt.

Someone, presumably Rich Paul of Klutch Sports, floated in off-the-record fashion that Davis has no interest whatsoever in a long-term deal with the Celtics should they trade for him on July 1, the first day the Celtics are eligible to do so.

In 2007, Kevin Garnett’s agent, Andy Miller, publicly sent the same message to the Celts, saying there was no way he would be traded to Boston. Not interested.

Funny, but wasn’t that a Celtics jersey that Kevin Garnett was wearing Thursday night, sitting next to Metta World Peace in his Lakers jersey? They’re friends now. They were on opposite sides in the 2008 NBA finals won by Boston.

Ainge didn’t let an agent’s words shut him down then and just because he’ll turn 60 next month doesn’t mean he has lost any of the gumption from his Brigham Young days that drove him the length of the court to beat Notre Dame in a memorable NCAA tournament game 38 years ago.

That was the beginning of a decade dominated by the Bird-Magic finals. Long before, the rivalry featured Russell vs. Wilt. In 2008, Paul Pierce’s Celtics defeated Kobe Bryant’s Lakers. A sign of the times: Now it’s the agent vs. the GM.

The Pelicans could have caved and let Davis become the perennial All-Star that LeBron needs to turn the Lakers into contenders, but decided to wait and see what Ainge offers in July. Now Ainge has five months to try to figure out his chances of making a long-term Celtic out of Davis. If he doesn’t believe he can sign Davis, he’ll make an offer commensurate with a one-year rental and it likely will be rejected. If Ainge is confident he can keep him long-term, then he’ll have to part with Jayson Tatum.

Trading Tatum, 20, will require taking a deep breath. He’s second on the Celts in scoring (16.3), rebounding (6.2) and minutes (31), and hasn’t reached his ceiling.

Tatum makes a team better. Davis transforms a franchise, and in the case of the Celtics could turn them from contenders to represent the Eastern Conference in the NBA finals to contenders to win it all.

Davis ranks second in the NBA in scoring (29.3) and blocked shots (2.6), fourth in rebounding (13.3) and seventh in steals (1.7). He stays out of foul trouble and shoots .812 from the line.

Surround Davis and Kyrie Irving with tough, unselfish competitors like Marcus Morris Sr. and Marcus Smart, and the Celtics are on their way.

As the Patriots, many of whom were in attendance Thursday night, showed in winning a sixth Super Bowl in 18 years, tough and smart go a long way.

Coach Bill Belichick was among the Patriots on hand but wasn’t believed to be scouting LeBron as a potential replacement for Rob Gronkowski in the event the tight end retires. As superstar/GM of the Lakers and one of the All-Star squads, James is plenty busy as it is, but he would make a heck of a tight end or defensive end. GM? We’ll see.

THEN, THE GAME

Rajon Rondo didn’t have time to think.

Not a moment to realize he was on the court he grew up on in the uniform of a rival. No time to ponder that Garnett, his professional big brother, and his son Rajon Jr. were both watching or that he’d missed every buzzer beater he’d ever attempted in the NBA before.

Even a split second of reflection on how badly this Lakers team needed him to make the shot would have been too much.

So he didn’t think. As the ball crowd-surfed above the hands in the paint, he readied himself. He caught the ball, and pivoted as he jumped, squaring his body in the air and pushed it toward the basket from just left of the lane.

It drained through the net without touching the rim, sending the same Garden crowd that cheered him in introductions home disappointed after a Celtic loss.

“Just get it. Actually it’s simple. Tyson (Chandler) did a (great) job with the offensive tip,” said Rondo, who had 17 points, 10 assists and seven rebounds. “I practice those shots all the time. Couldn’t imagine it here in the Garden, though. It’s surreal. It’s unbelievable.”

The magnitude of that moment wasn’t lost on Coach Luke Walton or James.

“It was a perfect ending,” Walton said “He’s got his son in here before the game and you can see how much love he has for this city, and this building. Being able to share that with his son and the ball finding him at the end of the game … For him to knock that down was for me and Laker fans a beautiful ending to the game.”

James agreed.

“I think for Rondo, he couldn’t even dream of that moment. To be back here where he won a championship,” James said. “For him to get his hands on that ball at that moment and be able to knock that down, it was a storybook ending.”

Rondo was 20 when he got to Boston, technically a man but still growing up. He spent nine seasons as a Celtic and won a championship in green in 2008 against the Lakers. Garnett was one of the guys he looked up to and learned from. It mattered to the Laker guard that Garnett was in the building for that shot.

“That’s my brother,” Rondo said, smiling a bit.

Over the course of this season, it was one February win. But for a Laker team coming off a blowout loss and a lot of trade talk, it felt like a chance for a turning point bringing them over .500 at 28-27 and moving within 11/2 games of the playoffs.

Whether or not it does, it will remain special to Rondo.

“This is one I’ll be playing for the rest of my life,” he said. “I’ll never forget it.”