The Heat scored the first 16 points of the second half and weren't in trouble again. Miami (54-25) leads the Pacers (54-26) by a half-game in the East race.
Paul George scored 22 for Indiana, which got 18 from David West, 12 from Luis Scola and 11 from Lance Stephenson. Pacers center Roy Hibbert had only five points and one rebound, grabbing it with just over 2 minutes left in the game.
Miami has games against Atlanta, Washington and Philadelphia left. Win them all, and the Heat would have home-court advantage through at least the East finals - which went seven games against Indiana last season.
The Pacers - who sat their starters against Milwaukee on Wednesday in an effort to rest for this one - still play Oklahoma City and Orlando.
In the opening minutes of the second half, a predictably tight game turned into a surprise blowout.
The Heat were up three at the half, then opened the third on a 16-0 run. Chalmers opened the barrage with a 3-pointer, James hit a pair of free throws after taking a hard foul from West in transition, and a steal and layup from Toney Douglas forced the Pacers to call time down by 10.
Miami was just getting started.
James got fouled by Stephenson and turned that into a three-point play, and consecutive putbacks by Haslem off misses by James at the rim pushed Miami's lead to 17 with 8:13 left in the third.
That led to Indiana's second timeout of the quarter.
And a couple of minutes later, the Pacers were up to more timeouts taken since halftime (three) than points scored (two). Indiana's first field goal of the half came when Bosh was called for goaltending on a shot by Luis Scola with 6 minutes left.
Miami's lead was eventually as much as 23, and it was 76-54 when the Pacers started to make things look plenty interesting, if only for a few moments.
Indiana scored 13 straight points, getting within 76-67 early in the fourth. But Evan Turner was whistled for a technical foul after arguing a non-call from two possessions earlier, Ray Allen made a free throw to end the Heat drought, and that started a 9-0 rebuttal run by the Heat.
Rashard Lewis ended that spurt with a dunk, good enough to earn him a chest-bump from James moments later, and just like that Miami was up by 18 again.
Neither team led by more than five in the opening half, after which Miami held a 45-42 lead.
James made four jumpers in the first 5 1/2 minutes, then missed all three of his shots in the remainder of the half, but still went into the break leading all scorers with 17 points.
There were two things of note from the opening 24 minutes: Indiana had 10 turnovers to Miami's three, and Pacers center Roy Hibbert was no factor.
Hibbert, the 7-foot-2 center who has simply toyed with Miami plenty of times in the clubs' recent meetings, played 16 first-half minutes with basically nothing to show for his time. He went into the break with no field-goal attempts and no rebounds - the first time he's ever logged that many minutes in a half without at least one shot or board.
NOTES: Miami kept Dwyane Wade (hamstring) out for the ninth straight game, and Greg Oden was still sidelined by back spasms. ... Haslem is Miami's all-time leader in offensive rebounds, grabbing the 1,506th of his career in the second quarter. ... From the Department of Go Figure: Miami went 0-4 against Brooklyn, Indiana went 4-0 against Brooklyn, so the Heat and Pacers went 2-2 against each other. ... All Game 1s in the conference-quarterfinal round will be April 19 or 20. ... West fouled out with 3:21 left, and Indiana down 14.