Jayson Tatum, Boston Celtics rose to Joe Mazzulla's halftime ...

BOSTON -- Boston Celtics head coach Joe Mazzulla loves to push his players. On Sunday night, after the Celtics had fallen into a massive hole against the severely undermanned Philadelphia 76ers by halftime, Mazzulla issued a challenge.

With his team down 61-44 at the break, Mazzulla told Celtics players their effort was nowhere close to where it needed to be. The 76ers were torching them from downtown, shooting 10-of-19 from deep in the first half. The Celtics were just 7-of-27 from three over the first 24 minutes.

The Celtics were missing badly on the offensive end, and let that bleed over onto the defensive end. Mazzulla told his core group that if they were tired and wanted to waive the white flag, so be it -- he'd put in the bench and let them finish out the game. 

The other option was to lift themselves up and get back to playing at the level they know they're capable of. The Celtics chose the latter, and are now flying high after a huge comeback victory.

It didn't work right away. The Celtics scored 36 points in the third quarter, but that only shaved three points off their deficit. They trailed by as many as 26 points late in the frame.

Then Boston erupted in the fourth quarter to claim a 118-110 victory, marking the team's biggest comeback win of the Mazzulla era.

Joe Mazzulla issued a challenge at halftime

It sounds like Boston's fiery head coach had the "I'm not mad, I'm just disappointed" approach at halftime. The Celtics should have been out for revenge on Sunday night after an embarrassing loss to the 76ers in Boston on Christmas Day. Add in the fact that Philadelphia was without four of its top eight players, including Joel Embiid and Paul George, and there was no real reason for the Celtics to be in such a situation. 

"We just had to be honest with ourselves at halftime. Our competitive spirit wasn't where it needed to be," said Jayson Tatum. "Joe was like, 'Yo, if you are tired, just tell me. I'll sit you guys down and let the Stay-Ready Group play.' And we just had a choice to make.

"He kind of challenged us at halftime. The way we were playing in the first half was not representative of who we are as a team and as an organization. We took it as men and responded," added Tatum.

Jayson Tatum, Celtics caught fire in fourth quarter

Mazzulla gave his team a spark at halftime, but it didn't rage into a fire until late in the third quarter. The Celtics fell behind by 26 points with just under three minutes to play in the third when things clicked on both ends.

Over the final 15 minutes, the Celtics caught fire and erupted offensively. Boston went on a 54-20 run over the final 14:55, and outscored the 76ers, 38-16, in the fourth quarter. 

Boston went 20-of-27 from the floor over that 54-20 run while holding the 76ers to just 7-of-23 shooting. The three-ball was their friend again, as the Celtics hit 12 of their final 16 attempts from downtown. Tatum, Derrick White, and Sam Hauser hit three apiece over that stretch. 

Tatum led the way in the second half, scoring 25 of his 35 points. He scored 13 in the fourth, hitting 5-of-7 overall and 3-of-4 from deep in the final stanza. Jaylen Brown had 15 of his 21 points after halftime, while White poured in 14.

That outburst, sparked by Mazzulla's halftime pep talk, led to the largest comeback in the NBA this season.

"It brought the best out of us," Tatum said of Mazzulla's challenge. "That's how we're supposed to play. It took a little bit from everybody. Our competitive joy was there on both ends and it was just fun to be a part of."

Mazzulla was delighted over his team's response.

"I told the guys, in the NBA, you get few chances where you really see your guys do something special in the regular season, and I felt like their approach to that was there," said Mazzulla. "It looked like they really, really wanted to do what it took to win. They delivered and I was proud to coach them in this game."

Celtics three-game win streak

Boston has now won three straight for the first time since the start of 2025, which tipped off a long stretch of .500 basketball for the Celtics. They had to scratch and claw against a shorthanded 76ers team on Sunday and needed a Tatum buzzer-beater to beat the lowly Pelicans on Friday night, but it looks like the team is starting to find its identity again.

The Celtics have now won seven of their last 10 games. They have a huge test Tuesday night as their three-game road trip concludes with a visit to the first-place Cleveland Cavaliers. Boston and Cleveland split the first two matchups of the season, with each team winning on its home court.

More from CBS News