Paul Pierce scored 18 of his 27 points in the first quarter, Kevin Garnett added 23 and the Celtics wasted most of a 28-point lead before beating the Heat 95-85 on Friday night.
Ray Allen scored 17 for the Celtics, who prevailed despite missing 12 of 13 shots over an 8 1/2-minute span late in the game -- a drought that allowed Miami to make a huge comeback bid.
"We knew they were a good team and was going to fight back," former Miami forward James Posey, now in his first season with Boston, said afterward. "We were able to weather the storm for the most part."
Boston forced 24 turnovers, which it turned into 33 points.
"Shot ourselves in the foot," Heat center Shaquille O'Neal said, repeating a phrase he's used often in the season's early stages. "Got into a deep hole, climbed out of the hole. We just have to limit our mistakes."
Jason Williams scored 22 points and hit three 3-pointers to spark a 24-3 run, one that drew the Heat within seven points with 3:56 left. But the margin didn't get any smaller, and Miami lost for the 11th time in 15 games this season.
Udonis Haslem finished with 18 points and 10 rebounds, O'Neal had 13 points and 11 rebounds and Dwyane Wade managed only 10 points on 2-for-11 shooting for Miami, which opens a six-game road trip Sunday in Denver.
"I just played a bad game," Wade said. "Simple."
One night after beating the New York Knicks by 45, the Celtics had a slightly tougher time on the way to improving the league's best record to 13-2.
They actually trailed for 2 minutes, 55 seconds of this one.
And even though Wade and O'Neal were virtually nonexistent offensively for long stretches, the Heat still had a chance down the stretch against the surging Celtics.
"We let our guard down for a while but picked it up at the end," Pierce said.
Late in the third quarter came perhaps the most telling stat: With 1:08 left in that period, Miami had 20 turnovers and 19 field goals. Little wonder why, at that point, the Heat were down 81-53.
Somehow, despite hearing another round of boos at home, Miami found a way to rally.
"The game sort of became a game," Heat coach Pat Riley said. "We found a good combination."
Williams hit a pair of 3-pointers to end the third quarter, then added another 11 seconds into the fourth, and the Heat were alive. Daequan Cook added another 3 in the early stages of the final period, and when Williams hit again from beyond the arc with 3:56 left, Miami pulled to 86-79.
"I can't say we were playing bad," Allen said. "We got a little passive and they took the momentum away."
But Allen -- who was 3-for-17 -- made a tough leaner despite some solid defense from Wade with 3:35 left to snuff out the Miami run, and the Celtics would hang on from there.
Boston coach Doc Rivers used a boxing analogy at halftime, referencing the 1990 light heavyweight championship fight between Meldrick Taylor and Julio Cesar Chavez, one where Taylor had the bout well in hand before getting TKO'ed with two seconds left.
The Celtics were on the ropes in the final minutes. The Heat never landed the knockout blow.
"We'll take the win," Rivers said. "We earned that lead."
When the teams met two weeks ago in Boston, the Celtics wasted a 15-point lead in the final quarter before escaping with a one-point win.
They tried to put the Heat away much sooner this time.
Cook's 3-pointer with 50.9 seconds left in the first quarter got Miami within two, 26-24. But the Heat went 5 1/2 minutes without another field goal, and Boston used a 14-2 run -- fueled by two layups from Posey -- to go up 40-26 with 8:36 left in the half.
Boston led by 21 late in the half before going into intermission with a 59-41 lead -- meaning, in a span of 25 hours and six quarters, the Celtics had outscored foes by a whopping 63 points.
The onslaught didn't stop there, either.
Pierce hit 3-pointers on consecutive trips early in the third quarter, pushing the edge to 71-46. The margin grew to 28 late in the quarter, before the Heat came to life.
"It's just frustrating," Wade said. "We put ourselves too far down. We've got to stop doing that."
Heat G Smush Parker was inactive again and not with the team, which is continuing to investigate an altercation he allegedly had with a valet parking attendant earlier in the week. ... Boston had a three-on-none break during the first half, after a deflection, and Garnett got an easy dunk. ... Celebrity sightings included tennis star Maria Sharapova, in town for a photo shoot, and actor Matt Damon.