MIAMI – LeBron James walked toward Mario Chalmers in the final minute with a contented look.

He punched his teammate twice in the chest. Fitting, because James and the Miami Heat have now landed two blows against the Boston Celtics.

James scored 24 of his 35 points in the second half, Dwyane Wade added 28 and the Heat used a late 14-0 run to pull away and beat the Celtics 102-91 in Game 2 of their Eastern Conference semifinal series Tuesday night.

“Now the mental discipline begins,” Heat Coach Erik Spoelstra said. “This thing is just getting started.”

Chris Bosh finished with 17 points and 11 rebounds for Miami, which leads the best-of-seven series 2-0.

Boston tied the game at 80 on a pair of free throws by Paul Pierce with 7:10 left. The Celtics missed their next six shots and Miami pulled away, taking command of both the game and the series, which doesn’t resume until Saturday night in Boston.

“That’s our staple. We know the only way for us to win games, especially in the playoffs, is to play defense,” James said. “Everyone has each other’s back. If one guy gets beat, another steps up.

“They made a run, a heck of a run … but we just kept grinding, kept playing our principles and we finally wore them down.”

Rajon Rondo played through a balky back to score 20 points and add 12 assists for Boston, which got 16 points from Kevin Garnett and 13 from Pierce. The Celtics have rallied from an 0-2 deficit in a best-of-seven series just once.

Jeff Green scored 11 and Delonte West added 10 for the Celtics, who got only seven from Ray Allen on 2-for-7 shooting.

Even for a franchise with such fabled history as the Celtics, an 0-2 deficit represents a colossal challenge. This is the ninth time Boston has dropped the first two games in a best-of-seven series. In the previous eight, the Celtics prevailed only against the Los Angeles Lakers in the 1969 NBA finals.

The last time Boston lost the first two games of a playoff matchup was in 2004, when it was swept by Indiana. The current core of Celtics had lost Game 1s four other times before this series, then bounced back to win Game 2 each time, against Chicago and Orlando in 2009, then Cleveland and the Lakers in 2010.

Not this time.

“Nothing we can do about it,” Celtics Coach Doc Rivers said. “We’ve got a third game and we’ve got to take care of that. Whatever the past is, it is.

“They’ve won two games at home, but we can’t allow them to play like this or it’s going to be tough at our place.”

The Celtics had more than a chance to avoid the 0-2 hole.

James scored 12 points in the third quarter, one more than he managed in the first half, to help Miami take a 72-67 cushion into the final 12 minutes.

James then added the first basket of the fourth, but Boston answered with a 13-6 run over the next 4 minutes to knot the game at 80.

That’s when Miami’s big run began, including a three-point play when James dunked and got fouled after Joel Anthony kept an offensive rebound alive. Chalmers started it all with a 3-pointer, his only points of the night, off a pass from Wade, and Miami was on its way.

“Great trust,” Spoelstra said.

Jermaine O’Neal had a chance to end Boston’s drought with 4:53 left, but his dunk was partially blocked by Anthony and bounced off the rim.

James hit a long jumper from the left corner 17 seconds later, pushing the Heat lead to 92-80, their biggest to that point.