Paul Pierce scored 17 of his 26 points in the third quarter as the Celtics erased a 19-point deficit and went on to consecutive wins for the first time since late November against Oklahoma City and Orlando.
Boston, which beat Indiana 94-75 on Friday night, had lost four consecutive road games.
Lou Williams scored 21 of his 28 points in the first half for Atlanta, which has lost two in a row.
The Hawks got off to a fast start, then fell apart in the third quarter as Boston began doubling ballhandlers on the perimeter and clamping down on Atlanta inside.
Atlanta was just 2 for 14 from the field in the third and trailed 71-62 heading to the final period.
KNICKS 114, MAGIC 106
In Orlando, Fla., Carmelo Anthony scored 16 of his 40 points in the fourth quarter, helping New York outlast the Magic.
J.R. Smith added 18 points off the bench.
Arron Afflalo and Jameer Nelson each had 29 points to lead the Magic
PACERS 95, BUCKS 80
In Indianapolis, Roy Hibbert had 20 points, 15 rebounds and five blocked shots to lead Indiana over Milwaukee.
Hibbert grabbed a career-high 11 offensive rebounds as the Pacers won their seventh consecutive home game.
Monta Ellis led the Bucks with 21 points.
NETS 113, KINGS 93
In New York, Brook Lopez scored 18 points in 17 minutes to lead six players in double figures, and Brooklyn beat Sacramento.
DeMarcus Cousins had 28 points and 11 rebounds for the Kings.
ROCKETS 112, CAVALIERS 104
In Cleveland, James Harden scored 29 points, including 16 in the fourth quarter, and Houston defeated the Cavaliers.
Kyrie Irving led Cleveland with 30 points.
TRAIL BLAZERS 102, TIMBERWOLVES 97
In Minneapolis, Nicolas Batum and Wesley Matthews each made five 3-pointers and scored 26 points to lead the Portland over injury-depleted Minnesota.
Nikola Pekovic led the Timberwolves with 21 points but left the game in the third quarter because of a left hip strain.
Only hours earlier, Minnesota learned it lost star forward Kevin Love to a broken right hand for the second time this season when an MRI confirmed the injury.
SPURS 109, 76ERS 86
In San Antonio, Tony Parker scored 20 points and Tim Duncan had 16 points and eight rebounds as the Spurs beat Philadelphia.
Spencer Hawes had 22 points to lead the 76ers.