Atlanta opened the final quarter with a 10-2 run, pulling to an 82-72 lead on Zaza Pachulia's two free throws with 8:34 to play. The Hawks pushed their lead to 88-76 on Bibby's free throw with 4:44 to go.
Pierce's basket in the lane cut it to 88-80, but Boston never made a threat the rest of the way.
The Hawks, who entered the game fourth in the league in scoring and coming off a win over the Knicks on Wednesday, came out looking to run and controlled the tempo early, jumping to a 14-6 edge in the opening 5 1/2 minutes, before the Celtics tightened up defensively and forced it into a half-court game.
"When you've got a chance to beat a team on the road and you're playing well, everybody looks mature," Boston coach Doc Rivers said.
NOTES: Boston F Brian Scalabrine was back in uniform after missing Wednesday's win over Utah with back spasms. ... Red Sox DH David Ortiz was seated courtside and got a big cheer when he was shown on the Jumbotron. ... Perkins was whistled for a technical for throwing an elbow after scoring a basket in the fourth quarter.
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