BOSTON — 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 3-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.

Indiana missed nine straight shots and committed four turnovers during the drought that lasted more than six minutes. Brown scored 10 on his own during the run and had 24 at the half; he opened the third quarter with two quick baskets to give the Celtics a 61-52 lead.

But Siakam also came out hot in the second half, hitting four baskets in the first four minutes – a pair of 2s and a pair of 3s – to make it a two-point game. Boston pulled away again – this time for good, scoring 16 of the next 21 points.

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.”