NEW YORK — Joe Mazzulla has referenced the Celtics’ horrible loss to the Nets last March – when they blew a 28-point lead – multiple times this season. It provided some of his biggest lessons as a first-year head coach. It made him study momentum, among other things, to make sure something like that never happened again.

Facing the Nets for the first time since that disastrous loss on Saturday night, the Celtics were reminded why their opponent was so tough that night in March.

These Nets, while much less talented than the Celtics, are tough. They were playing the second night of a back-to-back. They were missing key players, including Ben Simmons. That didn’t stop them from hanging tough for most of the night at Barclays Center, where they erased several deficits.

But these Celtics, with a few new pieces, are a different team.

Despite Cam Thomas and the Nets’ best shot, the Celtics were too much to handle. So far, they’re not letting history from last season repeat itself. Jayson Tatum scored 32 points, including his 10,000th career point, and the Celtics pulled away late for a 124-114 victory over the Nets with a Boston-heavy crowd cheering them on in Brooklyn.

Jaylen Brown had 22 points and Jrue Holiday added 18 points with 10 assists as the Celtics – who were without Derrick White – improved to 5-0 and remained the only undefeated team in the NBA.

The Celtics held a commanding halftime lead and let it slip but never ultimately gave it away. They led by a possession to start the fourth quarter before pulling away midway through the period, with the bench unit and several starters making key plays down the stretch. Holiday hit a 3-pointer with 6:31 left before Tatum drilled a devastating step-back 3-pointer to put the Celtics up double digits. Boston was never threatened again as they made all the plays late to hold on.

Other takeaways:

– Tatum made one of his strongest moves of the season to earn his 10,000th career point, which was fitting as it displayed just how much of an elite scorer he’s become. With five minutes left in the second quarter, Jaylen Brown won a jump ball that was corralled by Jrue Holiday, who passed to Tatum at the top of the key. With his back against Cam Thomas, Tatum blew by the smaller guard before making a spin move at the rim and finishing an and-one with his right hand.

As he stepped to the free throw line, the Celtics fans at Barclays Center started showering Tatum with MVP chants. He sunk the free throw to give himself 10,000 career points, then earned even louder MVP chants when he stepped to the line again later in the quarter.

At 25 years, 246 days old, Tatum became the 10th-youngest player in NBA history to score 10,000 points. He also became the first in league history to score 10,000 points with 1,000 3-pointers.

– After having trouble with the Nets for most of the first half, they finally created some breathing room with a strong end to the first half that included an 8-0 run over the final 1:10 – capped by Tatum’s 3-pointer at the buzzer – which gave them a 12-point halftime lead. They scored at least 70 first-half points for a third consecutive game, and they’re now averaging 74 points in the first half over that stretch.

But the Celtics nearly gave it all back to start the second half as the Nets went on a 12-2 run to open the third, which set up a close finish before Tatum and the Celtics pulled away.

– The Celtics, for a third consecutive game, started hot offensively as they began 9-for-15 from the field – including eight points from Tatum in the opening 2:45 – as they built a nine-point lead. But they cooled off, and the Nets outplayed the Celtics bench units to take a five-point lead in the second quarter.

– Luke Kornet, though he’s slotted as the primary backup big behind Kristaps Porzingis and Al Horford, hasn’t gotten much time in the rotation to start the season but had a strong surge in the second quarter to help the Celtics regain their footing after they fell behind by five. Horford found Kornet underneath for an easy bucket, then Kornet forced a miss from Cam Thomas before running the floor hard in transition where Jrue Holiday found him at the rim for another layup to cap Kornet’s personal 4-0 run. Kornet also made a key three-point play in the fourth quarter that helped the Celtics hold off the Nets.

– The Celtics continued to crash the offensive glass with success as they scored 14 second-chance points in the first half off six offensive rebounds. Horford gave them an early spark with two putbacks. The Celtics finished with 19 second-chance points.