Jrue Holiday scored 20 points and Elton Brand had 13 points and 10 rebounds as host Philadelphia forced a seventh game in its Eastern Conference second-round series with Boston.
Andre Iguodala and Evan Turner scored 12 points apiece as the 76ers rebounded from a loss for the third time in the best-of-seven.
Paul Pierce had 24 points and 10 rebounds and Kevin Garnett added 20 points and 11 rebounds for Boston, which hosts Game 7 on Saturday.
Philadelphia used stingy defense to win Game 6 and held the Celtics to 33.3 percent shooting from the field while forcing 16 turnovers.
The 76ers led by four points with 10 minutes to play before tallying seven straight points to take the first double-digit lead of the contest. Holiday scored back-to-back baskets to start the surge and Lou Williams hit a runner to cap it and give Philadelphia a 70-59 with 7:15 remaining.
A 3-pointer by Pierce trimmed Boston’s deficit to 80-75 with 32.3 seconds left before Holiday hit two free throws to help seal it.
Williams tallied 11 points for the 76ers, who were just 17 of 28 from the free-throw line and were outrebounded 48-37.
Boston led 36-33 at halftime despite shooting just 31.7 percent from the field. The 76ers shot 40 percent in the opening half, but missed 13 of their final 15 shots while scoring just 11 second-quarter points.
GAME NOTEBOOK: Boston guard Avery Bradley (shoulder) missed his second straight contest. … Brand is averaging 16 points over the last two games after averaging just 4.3 points over the first four games. … Celtics’ Game 5 hero Brandon Bass scored just eight points on 2-of-12 shooting . … Iguodala went 3 for 7 from the free-throw line and is just 13 of 29 in the series.