Jaylen Brown matched his career playoff high with 40 points, 10 of them to help Boston run off 20 points in a row in the first half to take the lead for good, and the Celtics beat the Indiana Pacers 126-110 on Thursday night to open a 2-0 lead in the Eastern Conference Finals.

Following up on Game 1, when his three-pointer with 5.7 seconds left in regulation forced overtime, Brown helped Boston turn a five-point first-quarter deficit into a 15-point second-quarter lead.

Jayson Tatum and Derrick White scored 23 points apiece and Jrue Holiday had 15 points and 10 assists for the top-seeded Celtics, who lost Game 2 in both of their previous series this postseason.

Pascal Siakam scored 28 for Indiana, which returns home for Games 3 and 4 on Saturday and Monday night. Tyrese Haliburton, who had 25 points and 10 assists in the series opener, had 10 points and eight assists Thursday before leaving the game in the third quarter because of a sore left leg.

One game after the Celtics jumped to a 12-0 lead and Indiana spent the rest of the first half clawing its way back, the lead changed hands 10 times in the opening quarter, with the Pacers holding a 27-22 edge with 1:14 left.

Then Boston scored the next 20 points.

During the longer than six-minute stretch, Indiana missed nine straight shots and turned the ball over four times. Brown led the Celtics to a 61-52 advantage in the third quarter after scoring 10 points on his own during the run and 24 points at the half.

However, Siakam also had a strong second half, scoring four points in the first four minutes of play (two twos and two threes) to cut the deficit to two points. Boston took a commanding lead once more, scoring 16 of the last 21 points to seal the victory.

Indiana never got within single digits again.

Brown scored 26 points Tuesday night, when the Celtics won thanks to some unforced errors by the Pacers — especially Haliburton — down the stretch. On Wednesday, Brown was left off the All-NBA teams; last year’s selection to the second team qualified him for a five-year supermax extension that made him the highest-paid player in the NBA.

Asked if he needed to talk to Brown about focusing on the team, instead of an individual snub, Celtics coach Joe Mazzulla said before the game, “He’s a very mature guy, so I don’t have to.”

“He has a great outlook on life. He knows what’s important and what’s not,” Mazzulla said before the game. “He works really hard, and he knows who he is as a person and a player. That’s the most important thing.”