"It was the two bench guys who really put the nail in the coffin against us," Drew said.
After trailing 43-38, the Hawks took the lead with an 11-0 run, capped by a three-point play by Devin Harris with 4.3 seconds remaining in the first half. James then launched a buzzer-beating jumper over Horford to cut Atlanta's halftime lead to 49-45. Following a review, officials ruled the shot was not a 3-pointer.
The Heat trailed only 57-56 early in the third period before the Hawks stretched the lead with 10 straight points. Korver had two 3-pointers before Smith's two-handed jam capped the run, giving Atlanta its biggest lead at 67-56.
Allen, who had a three-point play after Battier's first 3-pointer of the fourth quarter, gave Miami its first lead of the second half at 74-73 with a layup. Two free throws by James capped the 13-0 run.
"You can't get comfortable with them," Korver said. "They showed why they're a championship team. In the fourth quarter, in winning time, they had a lot of guys step up and make plays."
Mario Chalmers had 14 points for Miami.
NOTES: Miami G Mike Miller did not make the flight to Atlanta due to ear problems resulting from a head cold. Spoelstra said he hopes Miller joins the team for Thursday's game at Chicago. ... Heat F-C Chris Andersen suffered a sprained left foot and was in a walking boot after the game. ... Chalmers left the game less than 2 minutes into the second half and was limping after appearing to roll his right ankle. He returned after missing only a few minutes. ... Drew said he hopes the team adds a guard if it makes no other trade-deadline move. G Jannero Pargo's second 10-day contract expired, and Drew said he must monitor Harris, who has had problems with his left foot. ... Celebrities in the sellout crowd of 18,238 included Atlanta Falcons quarterback Matt Ryan and receivers Julio Jones and Roddy White and former heavyweight boxing champion Evander Holyfield.