BOSTON -- Brandon Bass scored 15 of his 27 points in the third quarter as Boston dominated Philadelphia in the second half and moved within one victory of advancing to the Eastern Conference Finals with a 101-85 victory over the 76ers on Monday night.
Kevin Garnett scored 20 points, Paul Pierce finished with 16 points and Rajon Rondo had his third straight double-double, finishing with 14 assists and 14 points.
The Celtics lead the series 3-2 and can wrap it up with a win in Game 6 on Wednesday night in Philadelphia.
Boston's Greg Stiemsma finished with 10 points, going 5-for-5 from the floor, and Bass led the Celtics to a huge advantage at the foul line, making nine of his 10 free throws. Pierce was 9-for-9 as Boston went to the line 33 times and made 26, while Philadelphia made 10 of 16 free throws -- not nearly enough to overcome poor shooting in the second half.
Elton Brand led Philadelphia with 19 points. Lavoy Allen scored 12, Evan Turner had 11 points and 10 assists and Spencer Hawes and Jrue Holiday scored 10 apiece for the Sixers.
Philadelphia came back to win Game 4, 92-83, after trailing by 18 in the third quarter, but couldn't recover after the Celtics took over the lead in the third quarter and started to pull away.
The Celtics scored the first six points of the fourth quarter, pulling away to an 81-66 lead on a pair of free throws by Pierce. Philadelphia went without a point from Allen's jumper with 50 seconds remaining in the third, cutting the lead to 71-66, until Allen's layup with 7:52 left in the game got Philadelphia to 81-68.
Rondo came right back with a three-point play and the Celtics continued to roll, keeping the margin too wide for the Sixers to come up with another big rally.
The Sixers looked strong early and led most of the game, but Boston caught up early in the third and took control with two big runs, oddly starting the first when Pierce was called for a clear-path foul.
Andre Iguodala was about to take off alone on a fast break with 8:00 left in the third period and Philadelphia leading 57-53. It turned out to be a good play because Iguodala missed both free throws and the Sixers turned it over after the inbounds pass, and the Celtics took off on a 10-0 run.
Bass converted two foul shots to tie it at 57-all, and Bass put the Celtics up on a dunk off a pass from Rondo. Bass grabbed a turnover at the other end, and Ray Allen took it for a layup, putting Boston up 63-57 as the reinvigorated crowd roared.
Allen pulled Philadelphia within 63-62, but Bass continued his surge with a jumper and the Celtics closed out the period on a 10-2 run, leading 75-66 at the end of the third.
The Sixers had five offensive rebounds in the first quarter and converted nine points out of them, outscoring the Celtics 9-0 on second-chance points.
Philadelphia also went 13-for-23 from the floor while taking a 27-23 lead at the end of the first period.
The Celtics came out stronger in the second quarter, tying the game when Allen hit a 3-pointer and Garnett converted a three-point play to make it 33-33. Garnett only had four points in the first quarter, then carried the Celtics in the second, scoring 10 while keeping Philadelphia from pulling away.
Boston still trailed 50-47 at halftime, keeping it close by holding Philadelphia to just two attempts from the foul line, where the Sixers went 1-for-2.
Notes: Avery Bradley sat out for the Celtics with a separated left shoulder, which has bothered him throughout the season. ... Brand got off a shot at the end of the first quarter, but the officials ruled it came after the buzzer and waved it off. The Sixers still led 27-23 at the end of the period. ... New England Patriots defensive lineman Vince Wilfork received a round of applause when he was shown on the big-screen monitor watching from the seats. ... Will Smith, a part-owner of the Sixers, also received a cheer, as did comedian Chris Rock. ... The Celtics did not attempt a free throw in the first quarter.