Rondo triple-double not enough to lift Celtics
Henry Sims had a career-high 24 points and a team-high nine rebounds for the Sixers, who have won two of their last four after a 26-game losing streak.
Thaddeus Young and Elliot Williams chipped in 15 points apiece for Philadelphia.
Rajon Rondo recorded his 29th career triple-double with 11 points, 16 assists and 11 rebounds for Boston, but committed seven of his team's 22 turnovers.
Jerryd Bayless scored 23 points and Jeff Green contributed 15 as the Celtics dropped their seventh straight game.
The Sixers led by as many as eight points in the first quarter, but Bayless had 12 points in the second and Chris Johnson's layup in the final minute gave Boston a 51-49 advantage at the break.
There were four ties and five lead changes in the third quarter, which Philadelphia capped with an 11-2 surge to claim a 76-71 lead going into the fourth.
Hollis Thompson's 3-pointer with 9:14 remaining allowed the Sixers to match their largest lead at 84-75 before the Celtics crawled to within 89-86 on Green's three-point play midway through the period.
Carter-Williams answered with a layup and a jumper and Young had three baskets in the final three minutes to help maintain a comfortable margin.
GAME NOTEBOOK: Celtics G Avery Bradley missed his second straight game with a strained right Achilles and also will sit Saturday at Detroit. ... Rondo's last triple-double was Jan. 25, 2013, the game in which he tore his ACL. ... Philadelphia is 3-28 in its last 31 games, with two of the three wins coming at Boston.