Cooper Flagg labored to lead the Mavericks with a game-high 36 points in a 110-100 loss to the Celtics Tuesday night in Dallas.
Cooper Flagg labored to lead the Mavericks with a game-high 36 points in a 110-100 loss to the Celtics Tuesday night in Dallas.Tony Gutierrez/Associated Press
DALLAS — The Celtics’ locker room was sullen prior to the matchup against the host Mavericks at American Airlines Center after learning Anfernee Simons, a popular and productive teammate, had been traded to the Bulls.
Yet, the mission never changes for this surprising team. The shorthanded Celtics withstood a stellar performance from Maine native Cooper Flagg in his first game against his boyhood favorite NBA team as Jaylen Brown and Payton Pritchard, thrust into a new role as a reserve, combined to lead the Celtics to a 110-100 victory Tuesday night in Dallas.
Brown scored 33 points to go along with 11 rebounds while Pritchard, coming off the bench for the first time all year, added 24 points with 7 assists as the Celtics led for the final 37:10.
Flagg, the Rookie of the Year favorite, scored a game-high 36 points for the Mavericks on 12-for-24 shooting but received little help with Caleb Martin the next-highest scorer at 13.
The Celtics moved Simons earlier Tuesday for center Nikola Vucevic but the deal is not likely to be official until Thursday. Boston still managed to shoot 49 percent with Luka Garza scoring 16 off the bench, hitting 4 of 4 from 3-point range.
It took until the second half for the Celtics to consistently sink 3-pointers and the long-range shot allowed them to build a comfortable lead after the Mavericks drew to within 54-48.
Sam Hauser and Baylor Scheierman hit consecutive triples to increase the Celtics’ lead to 11, 64-53.
After Flagg hit three free throws to bring the Mavericks to within single digits, 72-63, the Celtics ended the quarter on a 14-4 run.
Garza knocked down three 3-pointers in the final 3:58 of the period and Derrick White (11 points) snapped a skid with a wide-open corner 3-pointer as the Celtics took an 86-67 lead.
Flagg was aggressive in attacking the rim but the Celtics threw waves of defenders at him. He had 21 points after three quarters on 8-for-15 shooting. No other Mavericks player scored more than 11 points.
Brown led the Celtics with 25 points and Pritchard added 17. The Celtics were 6 for 12 from the 3-point line.
The Celtics looked to be in full control when they began the second period on an 18-5 run, sparked by Pritchard and a triple from Garza.
The Celtics controlled a 50-34 lead, but suddenly they went scoreless for a 3:05 span and managed just one more bucket the rest of the half.
The Mavericks also struggled to score but got a pair of baskets from Flagg to pull within 52-44 at halftime.
After scoring 15 points in the opening period, Brown managed 2 in the second as the Celtics went 8-for-21 shooting with four turnovers.
The Mavericks were 7 for 22 from the field and missed 8 of 9 3-pointers. Flagg led Dallas with 14 points and Martin added 11.
Brown and Pritchard combined for 32 of the Celtics’ 52 points while Derrick White’s shooting struggles continues (2 for 8) while Baylor Scheierman went scoreless in 14 minutes.
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— Boston Celtics (@celtics) February 4, 2026
With a shorthanded lineup, including the absence of Simons, Mazzulla opted to bring Pritchard off the bench for the first time this season. Scheierman took Pritchard’s spot in the starting lineup. Pritchard entered the game with the second unit at the 6:24 mark of the first quarter.
The Celtics were also missing Chris Boucher, the little-used forward, for personal reasons. It’s believed Boucher could be traded or waived at the deadline. The Mavericks were short five rotation players with Kyrie Irving, Anthony Davis, P.J. Washington, Brandon Williams and D’Angelo Russell all out.
Flagg, who was coming off a 49-point game in a 123-121 road loss against the Hornets last week, made his presence felt, scoring 8 points in the opening period, mostly against Brown’s defense.
But Brown was even better, offensively, scoring 15 points and grabbing 5 rebounds in the first 12 minutes as the Celtics took a 32-29 lead.
Pritchard scored 8 points off the bench in his six-plus minutes. Meanwhile, Celtics nemesis Caleb Martin, who burned Boston in that Eastern Conference Finals series in 2023, scored 7 points in 8 minutes for the Mavericks.
Both teams shot 50 percent in the opening period.
Gary Washburn is a Globe columnist. He can be reached at gary.washburn@globe.com. Follow him @GwashburnGlobe.