The Celtics punched the Cavaliers first and never looked back in rolling to a Game 1 rout. LeBron James took a literal shot to the jaw in Game 2 but kept right on scoring. So did the Celtics.

Jaylen Brown scored 23 points and Boston withstood a 42-point night by James to beat Cleveland 107-94 on Tuesday and take a 2-0 lead in the Eastern Conference finals. Terry Rozier added 18 points, while Al Horford finished with 15 points and 10 rebounds.

Boston improved to 9-0 this postseason at TD Garden. The Celtics have never blown a 2-0 series lead in the playoffs. “We’re going to fight,” Rozier said. “At this point we don’t care if we win by half a point. If we win, that’s all that matters.”

James added 12 assists and 10 rebounds. He scored 21 of Cleveland’s 27 points in the first quarter , tying his playoff career high for points in a period. His 42 points marked his fifth 40-point game of this postseason. James had just 15 points and missed all five of his 3-point attempts in the Cavs’ Game 1 loss.

But he didn’t seem to play with the same force after straining his neck in a first-half collision and the Cavaliers wilted in the second half, with the Celtics outscoring them 59-39. “I think I’ll be fine. I’m not going to lose sleep over it. You go out and when you lay everything on the line, at the end of the day, you can live with that,” he said. “They did what they had to do, and that was protect home, and now it’s our time to try to do that, as well.”

Kevin Love finished with 22 points and 15 rebounds for Cleveland.

As expected, Tristan Thompson started in place of Kyle Korver in the hopes his presence could energize what was a sluggish Cavs offense in Game 1. Thompson got Cleveland’s first basket of the night and helped to limit Horford’s effectiveness on the inside early on.

Korver added 11 points off the bench for Cleveland. But starters Thompson, JR Smith and George Hill combined for just 11 points on 5-of-17 shooting.

Tempers flared with 3:49 to play with Boston leading 97-89. Marcus Smart got in Smith’s face after Smith pushed Horford in the back to prevent a layup. Smith shoved Smart and the pair had to be separated. Smith was assessed a flagrant foul and both received technical fouls.

“I felt like it was uncalled for that type of play there,” Horford said. “We have each other’s backs. We moved on to the next play way and we locked in after that.”

Smith said there was no malicious intent on the play. “I blatantly pushed him. It wasn’t like I was trying to low bridge him or something. Just make sure he didn’t get it,” Smith said. “It was a good, hard foul.”

Boston’s balanced attack was effective again, with six players reaching double figures. Cleveland had 15 turnovers leading to 13 Boston points. The Celtics turned it over just six times.

Boston led 84-77 after three quarters and took command late in the fourth with the Cavs getting little offense other than from James. Cleveland’s starters were pulled with 1:48 left and the Cavs down 14.

James was on the attack from the opening tip. He turned the ball over the Cavs’ first possession. But it was one of his only miscues in the first quarter. James was also astoundingly efficient, using his dribble to create space, while he knocked down an assortment of jump shots. He finished the opening quarter 8 of 13 from the field and 4 of 7 from the 3-point line.

His momentum was stunted briefly at the 3:50 mark of the second quarter, when Jayson Tatum was whistled for a foul after catching James jaw with his shoulder as he attempted a steal. James stayed in the game and connected on one of his ensuing free throws, but then exited to the locker room with Cleveland leading 47-36.

The Cavaliers said James had a neck sprain. He returned after missing less than two minutes of game time.

Boston flurried just before the half, getting six points from Morris in the final minute to trim Cleveland’s lead to 55-48 at the break. “I think we just have a group of guys that really believe in each other,” Horford said. “Our group in tough times, we’ve always found a way.”