PHILADELPHIA -- As the 76ers -- minus four of their top eight rotation players, including stars Joel Embiid and Paul George -- opened up a 90-64 lead over the Boston Celtics with 2:56 to go in the third quarter, it looked like another rough loss was on the way for the defending champions.

But Celtics coach Joe Mazzulla kept watching his team's body language, judging when it might be time to pull the plug with a significant game on the way Tuesday in Cleveland against the East-leading Celtics.

"I was kind of studying their body language and it looked like they really, really wanted to do what it took to win," Mazzulla would say after the game. "So I kind of stuck with them."

Mazzulla's belief turned out to be warranted. Boston, after Ricky Council scored to give Philadelphia that 90-64 lead, completely turned the game on its head, closing it out with a 54-20 obliteration of the 76ers -- including going 12-for-16 from 3-point range over the final 15 minutes of game action -- to emerge with a 118-110 victory here at Wells Fargo Center.

"We just had to be honest with ourselves at halftime," Celtics star Jayson Tatum, who had 25 of his 35 points after halftime, said. "They had 20 points in transition. Our competitive spirit wasn't where it needed to be. Joe was like, 'Yo if you're tired, then just tell me. I'll sit you guys down, let the stay ready group play.' And we just had a choice to make.

"It was a long third quarter, it didn't go our way right away and we just had to keep fighting. But it brought the best out of us, it brought -- 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."

Before Derrick White drained a 3-pointer with 2:42 to go in the third off a Tatum assist -- one of his 11 on the night, 8 of which came after halftime -- the Celtics had gone 9-for-33 from 3-point range. But then the Celtics rattled off four straight to end the third -- two from White, another from Sam Hauser and one from Tatum -- as part of a 16-4 run that cut Boston's deficit down to 14 points to start the fourth quarter.

From that point on, the Celtics felt confident that if they stuck to their game plan, things would eventually break right for them.

And, once Tatum hit back-to-back 3-pointers to put Boston into the lead at 101-100 midway through the fourth quarter, he blocked a Tyrese Maxey 3-pointer to lead to a Luke Kornet fastbreak dunk and a Philadelphia timeout.

All told, the Celtics ripped off a 41-10 run over exactly an 8-minute span to flip the game around, and come away with a third straight victory for the first time in a month.

"I think so," said Jaylen Brown, when asked if it felt like a special game for Boston to pull off such a big comeback. "Just how easy it is to just call it a night and just throw the subs in and just come up with some type of excuse to give the media or whatever.

"We rallied back, we put the effort in, we turned it up, we stayed together and we persevered through a win even though we probably shouldn't have been down that much in the first place, but I think it's a credit to us that we was able to get it back on track in a hostile environment."

For Philadelphia, it briefly looked like the 76ers would be able to pull off a fifth win in six games -- none of which have come with Embiid on the court -- before the second half collapse. The question now, though, is whether Embiid and George could come back sometime this week.

Sixers coach Nick Nurse said before Sunday's game that both Embiid, who has missed 15 straight games with knee swelling and a foot sprain, and George, who has missed the past four with a finger injury, could play sometime this week.

Philadelphia plays at home Tuesday against the Dallas Mavericks -- in what could be the first game for Anthony Davis following Saturday night's shocking trade -- and Wednesday against the Miami Heat before playing Friday in Detroit and Sunday in Milwaukee.