The Celtics completed the largest comeback of the Joe Mazzulla era Sunday night, shocking the Philadelphia 76ers in a 118-110 victory.

Boston played one of its worst first halves of the season and trailed by as many as 26 points late in the third quarter, but Mazzulla’s club outscored Philadelphia 38-16 during a dominant fourth quarter.

The 26-point comeback equaled the largest by any NBA team this season. The Celtics hadn’t overcome a deficit that significant since coming from 32 points down to defeat San Antonio on April 30, 2021.

“I was proud to coach them in this game,” Mazzulla told reporters in his postgame news conference.

Jayson Tatum fueled the Celtics’ rally, finishing with 35 points on 13-of-20 shooting (5-for-8 on 3-point attempts), a season-high 11 assists and seven rebounds. Jaylen Brown tallied 21 points, 10 boards and six helpers. Kristaps Porzingis scored 18 points and blocked five shots, Derrick White went 5-for-9 from 3-point range and added nine assists, and Jrue Holiday made multiple winning plays in the closing minutes.

Tyrese Maxey scored 34 points for an oft-injured 76ers team that was playing without Joel Embiid, Paul George, Caleb Martin, Andre Drummond and Eric Gordon. Ex-Celtic Guerschon Yabusele scored 21 against his former team.

Maxey, the most productive and reliable member of Philly’s snakebitten Big Three, was too much for Boston to handle early on, outscoring the Celtics by himself (14-13) over the opening seven minutes. The Celtics didn’t help themselves offensively during this slow start, going 1-for-8 from 3-point range with misses by five different players.

Boston’s shooters settled in during an 11-2 run that featured a pair of Kristaps Porzingis threes, then went cold again over the final three-plus minutes of the first quarter. Tatum and Brown combined for just six points and two made field goals in the quarter, and the Sixers led 29-21 after one.

The Celtics played nearly half of that frame with Jaden Springer on the floor, with Joe Mazzulla giving the young guard another meaningful opportunity in Payton Pritchard’s absence. Pritchard sat out for the first time since April 2023 after landing on the injury report with an illness Sunday morning, snapping a streak of 132 consecutive regular-season appearances.

Maxey’s scoring pace slowed after Springer entered, but the latter missed two open corner threes during his seven-minute shift and watched the rest of the game from the bench. Springer’s second misfire was part of a succession of nine straight missed threes by the Celtics, who attempted 27 first-half triples but made just seven (26.9%). The Celtics’ 33.3% overall field-goal percentage before halftime was their worst in any first half this season. Their 44 points were their second-fewest.

In one emblematic moment, Holiday found himself wide open in the left corner as time wound down in the half. Rather than quickly letting a shot fly, the veteran guard took one extra dribble, causing his (made) 3-point attempt to leave his hand just after the buzzer sounded. Boston trailed 61-44 at halftime, with Holiday sitting at a team-worst minus-28 and Tatum at minus-23. (Every other Celtic was a minus-8 or better.)

“There was definitely a component that we weren’t playing as detailed as we needed to with Maxey scoring 23 points in the first half and (many of) those coming in transition,” Mazzulla told reporters. “But I thought we were getting really good shots. At one point, I looked at the box score and they were shooting 60% from three and we were shooting 26%. So I said we’re going to lose by 50 or it’s going to be a close game. I really liked our guys’ approach in the second half. Even when it wasn’t going well, we had a great approach. Just kind of chipping away at it, chipping away at it.”

The Celtics briefly pivoted from their 3-point-heavy approach in the third quarter, attempting just one in the first 5:58 after halftime. They began prioritizing attacking the rim against a Sixers team that was missing most of its top interior players, and that strategy yielded a quick series of up-close makes from Tatum, White and Porzingis.

It didn’t make a dent in their deficit, however, as the Sixers pulled further ahead as the quarter dragged on. One of the leaders of that charge was Yabusele, the 2016 Celtics draft pick who parlayed an impressive Olympic tournament into an NBA return after five seasons in Europe. The burly forward scored 12 of his 21 points in the third, hitting two 3-pointers and throwing down two monster dunks, one of which drew a technical foul for excessive celebration.

Yabusele’s first three put the Sixers up 77-56 and seemed to trigger a game-plan shift from Mazzulla. The Celtics reverted to their bombs-away mindset, and their open looks finally started falling consistently.

Sixteen of Boston’s next 25 shots came from beyond the arc. Eleven of those hit the mark. The Celtics trimmed the 76ers’ lead to 14 points by the end of the third quarter, then exploded in the fourth. After missing their first two field goals of the final frame, they made their next 10 in a row, including two threes by Sam Hauser (12 points; 4-for-7 from three) and three by Tatum, the last of which put Boston ahead 101-100.

Tatum blocked a Maxey three on the next possession, springing Luke Kornet for a transition dunk, then drove for a layup to cap a 23-6 Celtics run.

“In the first half, we weren’t making shots, and it was impacting some of our defensive details,” Mazzulla told reporters. “In the second half, we played through it and chipped away at it. We got stops. We got out. We were able to run. … I just liked our guys’ mindset. I was kind of studying their body language, and it looked like they really, really wanted to do what it took to win. So I stuck with them, and they delivered.”

Reserves Kornet and Hauser both were instrumental in Boston’s fourth-quarter takeover. The Celtics outscored the Sixers by 17 and 18 points with each of them on the floor, respectively, and Mazzulla played both over veteran big man Al Horford, who did not see the floor after halftime.

White checked back in for Hauser with 4:46 remaining and hit two late threes to help Boston pull away. It was Holiday, though, who played the role of Celtics closer, atoning for his forgettable first half by blocking a Maxey shot and drilling a dagger three in the final two minutes. Holiday also blanketed Maxey on another late-game possession, with his defensive foul overturned following a successful Celtics challenge.

The Celtics, winners of three straight for the first time since early January, will close out a three-game road trip Tuesday night against the Eastern Conference-leading Cleveland Cavaliers. They trail the Cavs by 5 1/2 games and split the teams’ first two meetings.

“At the end of the day, you try to build off these,” Mazzulla told reporters. “It doesn’t mean you’ll necessarily build off it tomorrow or the next day, but I just liked the guys’ approach and their mindset for this one particular game. We know we have it in us to do some stuff like that, so it’s important that you’re in some of these situations.”