MILWAUKEE -- Ray Allen wasn't so sure Boston would be able to pull it out in overtime.
The Celtics hadn't scored in nearly three minutes and were fading fast in their eighth game in 12 days.
"It was touch and go for a moment there because we couldn't score," said Allen, who spent the first 6 1/2 years of his career in Milwaukee and is ninth on the franchise's scoring list. "We couldn't get in a rhythm, but Paul got going and the free throw line saved us in overtime."
Did it ever.
Pierce scored 28 points and Allen finished with 27, combining to hit 23 of 24 free throws. Boston went 32-of-36 as a team. Milwaukee hit its share, too, going 30-of-38 with the teams combining for 62 personal fouls, nine technicals and one ejection.
"It was pretty grueling. I'm not going to lie. It was probably one of the more toughest stretches I've experienced in my career," Allen said of the Celtics' packed schedule. "We didn't make excuses or anything. We had to get a win tonight."
Allen and Pierce were without the final member of the Big Three, Kevin Garnett, after he fouled out with 1:48 left, but the pair managed to give the Celtics their sixth straight win over Milwaukee.
Bucks rookie Luc Richard Mbah a Moute, who finished with 14 points, hit two free throws to give Milwaukee a 95-93 lead, but Pierce answered with a 3-pointer off an offensive rebound by Garnett to put Boston up by one.
Garnett picked up his sixth foul moments later and Dan Gadzuric, who replaced an ejected Andrew Bogut, dunked for Milwaukee's only field goal in overtime, giving the Bucks a 97-96 lead with 1:07 left.
After the teams failed to score on Pierce's missed layup and a turnover by the Bucks, Allen was fouled with 24 seconds left, hitting both free throws to make it 98-97.
Richard Jefferson, who had 14 points, then missed a jumper over Pierce, and Allen hit two more from the line.
Trailing 100-97 with 10 seconds left, the Bucks opted for a short jumper by Gadzuric that he missed instead of a 3-point attempt to tie. Pierce grabbed the rebound, his seventh to go along with six assists, and hit both foul shots to finish 14-of-15 from the line.
"Overtime was good. After the first two minutes of just bad basketball on both sides, I thought overtime was really good," Celtics coach Doc Rivers said. "Paul was exhausted and you could see Ray had some great shots right before overtime, but playing eight games in 12 days, everything was front rim."
Milwaukee, already without leading scorer Michael Redd (right ankle) and Charlie Villanueva (hamstring strain), finished 1-for-11 in overtime after rallying from a 12-point deficit in the fourth quarter.
With the Celtics up 82-81, Pierce hit a jumper and Allen hit a layup for a five-point lead, but the Bucks came back without Bogut, who hit a layup and went hard into Garnett.
Garnett appeared to make contact with Bogut's face with an open hand, but officials immediately stepped in, assessing a double technical as Bogut and Garnett continued glaring at each other with 3:58 left.
"I tried to be aggressive and duck in when I could," said Bogut, who called the resulting ejection a tough play, but declined to criticize it. "We had a chance to beat them."
After officials conferred, the call stood and Bogut, who finished with 20 points, was ejected for his second technical after picking up one 5 minutes earlier in the quarter on a staredown with Leon Powe.
"I didn't get an explanation other than he was getting a second technical and getting thrown out," Bucks coach Scott Skiles said. "That's not the time in the game where I can get too caught up in it."
It appeared that Boston would pull away after that when Garnett hit a jumper, but Luke Ridnour answered with a 3 and Mbah a Moute converted a three-point play, giving Milwaukee an 89-88 lead, the Bucks' first since the first quarter.
Pierce answered with five straight points to put Boston back ahead 93-89, but Milwaukee sent it to overtime on Jefferson's 15-foot jumper and Ridnour's driving layup with 1.4 seconds left.
"It was a great game," Celtics forward Glen Davis said. "As long as we came out of here with a victory, that's all that counts at the end of the day."
Skiles said he thought Redd was trying to play on the upcoming two-game road trip to Denver and Utah, but acknowledged he's not sure when Redd would return. ... Celtics rookie G J.R. Giddens was sent to the Utah Flash of the NBA D-League on Saturday. He had not played so far this season.