BOSTON — The Chicago Bulls scored 21 points in the third quarter of Monday night’s game at TD Garden. Payton Pritchard nearly matched that output by himself. The Boston Celtics sixth man scored 19 of his season-high 28 points during a sensational third period against Chicago, launching five 3-pointers and burying all of them to power Boston to a 134-99 rout. Pritchard finished the night 10 for ...

Boston Celtics guard Payton Pritchard and Chicago Bulls guard Norman Powell chase down a loose ball during the first half of a NBA game at the TD Garden on Monday, Oct. 26, 2026, in Boston.

Matt Stone/Boston Herald/TNS

BOSTON — The Chicago Bulls scored 21 points in the third quarter of Monday night’s game at TD Garden.

Payton Pritchard nearly matched that output by himself.

The Boston Celtics sixth man scored 19 of his season-high 28 points during a sensational third period against Chicago, launching five 3-pointers and burying all of them to power Boston to a 134-99 rout.

Pritchard finished the night 10 for 16 and 7 for 10 from 3-point range, adding four assists and two steals in his 22 minutes. The Celtics outscored the rebuilding Bulls by 22 points during those minutes, making Pritchard one of four Boston bench players to post a plus-20 or better in the win (along with Sam Hauser, Neemias Queta and Hugo Gonzalez).

Jayson Tatum spearheaded the starters with 21 points on 7-of-17 shooting, plus seven rebounds and six assists. Paul George scuffled for much of the first half — and combined for 10 total turnovers with the typically reliable Derrick White — but came alive in the third to finish with 16 points.

The Celtics held Chicago to 39% shooting and forced 25 turnovers, which they turned into 39 points.

The win kicked off Boston’s first back-to-back of the season — one of six head coach Joe Mazzulla’s club will need to navigate before the end of November. The 2-1 Celtics will host the 0-3 Brooklyn Nets on Tuesday.

The Celtics came out humming offensively, hitting five of their first seven shots to trigger an early timeout by Bulls head coach Tiago Splitter. All five of those makes were assisted, including three on dishes from Tatum, who found Mitchell Robinson for a pair of dunks in the opening four minutes.

George connected on his first two 3-pointers. White added another. The Celtics led 15-8 at the first stoppage.

Chicago cut the deficit to one during a Celtics lull, but Boston closed the first quarter with a 14-3 run to push it to double digits. Gonzalez, who did not score in either of the Celtics’ first two games, helped fuel that push with a putback, a fast-break and-one layup off a Tatum steal and a catch-and-shoot corner 3.

Tatum shot it poorly in the first quarter (2 for 7) but closed the frame with a flourish, splitting Leonard Miller and Buddy Hield for a buzzer-beating layup that made it 33-21.

After 3s by Hauser and Pritchard stretched the lead to 16 early in the second, a series of Celtics miscues let Chicago back in the game. Boston turned the ball over on three straight second-quarter possessions — and four times in a six-play span — and lacked discipline defensively.

White had five turnovers before halftime, a total he reached in just two full games last season.

One White outlet pass sailed out of bounds because Gonzalez had his head turned. A Normal Powell jumper on the ensuing possession made it a three-point game, 46-43.

The Celtics eventually found their footing, responding to Chicago’s 15-2 run with a 10-1 run of their own. Gonzalez featured prominently in that one, too. The second-year wing flipped a pass to Queta for a lob dunk, blocked Jalen Smith from behind to set Tatum loose in transition and played the final 5:49 of the half.

Tatum scored eight points in the final 71 seconds of the half, capping it with a straightaway three over Josh Giddey with 0.8 seconds on the clock. His numbers at halftime: 19 points, six rebounds, five assists. Boston took a 66-54 lead into the locker room.

Fouls were an issue for the Celtics during the third quarter. Tatum checked out less than five minutes in after picking up his third and fourth in quick succession, and Chicago spent more than half of the period in the bonus.

That proved inconsequential, however, thanks to a Celtics hot streak powered by George, Hauser and especially Pritchard. Boston scored on five consecutive trips late in the third — Pritchard layup, Hauser 3, Pritchard 3, Pritchard 3, Pritchard 3 — to build a 30-point lead and turn the final quarter into a de facto practice.

Veteran point guard Mike Conley, who signed this offseason knowing he’d rarely see minutes behind White and Pritchard, made his Celtics debut at the start of the fourth quarter. Wing Ron Harper Jr. also saw his first action of this regular season, and first-round draft pick Chris Cenac Jr. made his NBA debut in garbage time.

Cenac, a smooth-moving 6-foot-11 big man out of Houston, hit a 3-pointer on his first touch.

Bulls top draft pick Caleb Wilson decked Gonzalez with a flagrant foul in the final minute, but Gonzalez remained in the game. The 2025 first-rounder finished with 13 points, five rebounds, one block and no turnovers. He played 24 minutes, including the final 12, and was a plus-34.

Tatum played deeper into the fourth quarter than most of the Celtics’ regulars, checking out for good with 6:52 remaining. It was unclear as of Monday night whether the team planned to play him, George or Robinson — all veterans with recent injury histories — against the winless Nets on Tuesday.

“I think at the end of the day, it’s twofold,” Mazzulla said pregame. “We trust the sports science team that we have. We trust the competition of those guys. At the same time, I think our locker room has been built on one through 15, 16 or 17 being able to impact winning. So it’s just a combination of all those things.

“At the end of the day, we have to do what gives us the best chance to win, and at the same time, keep those guys healthy and validate the whole locker room by putting guys in situations where they’ve got to win games for us.”

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