Trailing by five points entering the fourth quarter, the Pacers took an 86-84 lead on Williams' 3-pointer with 9 minutes left. Boston answered by scoring the next nine points, including Allen's 3 to cap the run, to open a seven-point advantage.
Indiana cut the deficit to 95-94 following Granger's 3-pointer and Williams' layup with 3 minutes remaining, but the Celtics regained a 101-95 lead on Pierce's jumper with 52 seconds left.
Allen scored 10 of the Celtics' first 12 points of the game, including a 3-pointer to give Boston a 10-0 lead. The Pacers fought back, taking a 13-12 advantage on Troy Murphy's two free throws later in the period.
Indiana opened its biggest lead of the game, 34-23, on Marquis Daniels' basket early in the second quarter, but the Celtics regained a 49-45 edge following Rajon Rondo's 3-pointer with less than two minutes left in the half.
In the third quarter, Boston extended its lead to 75-65 on Allen's jumper with 3 minutes left. The Pacers got within 82-77 after layups from Kareem Rush and Murphy to end the period.
Notes:@ Garnett missed his eighth consecutive game with an abdominal strain, and Perkins was out with a strained left shoulder. ... O'Neal missed his 12th straight game for the Pacers with a sore left knee, and Tinsley also missed the game with a sore left knee. ... Granger extended his streak of consecutive free throws made to 56. He finished the game 5-of-5 from the line. ... The Celtics have won six of their last seven games. Their only loss came Feb. 5 at Cleveland. ... The Pacers, who play at Detroit on Wednesday, dropped to 3-13 in the first game of back-to-backs this season.
Source: AP News