It was Boston’s fifth straight victory, and the fifth straight loss for Portland.
Paul Pierce scored 28 points, Kevin Garnett had 17 points and eight rebounds, and Rajon Rondo had 10 points and 10 assists as the Celtics built a 96-80 lead, then watched the Blazers score 15 in a row to make it a one-point game with 42 seconds left. Pierce dribbled down the 24-second clock, then fed it to Allen on the left side for the clinching 3.
Wesley Matthews scored 23 points and Andre Miller had 20 for the Blazers.
Allen was just 3-for-12 from the floor for nine points.
Pierce went 9-for-11 from the floor, making his first four 3-point attempts to help the Celtics shoot 57 percent as a team in the game. Shaquille O’Neal scored 14 points, and reserve Glen “Big Baby” Davis added 16 points and seven rebounds.
The Blazers led by as many as 11 points in the first half and had a 68-62 lead in the third before Boston scored 17 of the last 21 points in the quarter. The Celtics made it a 16-point lead in the fourth before the shots stopped falling.
Matthews hit a 3-pointer and added a layup, then Pierce airballed a 3-pointer before Brandon Roy scored on a fadeaway jumper to cut Boston’s lead to 96-95. After a timeout, Allen regained his touch, then Miller and LaMarcus Aldridge each missed 3-pointers in the closing seconds as Portland tried to get back in it.
Matthews hit 5-of-7 3-pointers for the Blazers, and Aldridge and Roy had 18 points apiece. Former UMass star Marcus Camby had nine rebounds and four blocked shots with zero points.
The Blazers have struggled in the fourth quarter in the past week, scoring just 42 points total in the final period in their last three games. They had 20 in the game before that — but they gave up 38 as the Utah Jazz rallied from a nine-point deficit to win 103-94.
This time, the fourth quarter was their strongest.
The Blazers led by 11 in the second before Boston scored 14 of the next 16 points, including a pair of 3-pointers by Pierce, and took the lead on a putback dunk by O’Neal that made it 44-43 with 90 seconds left in the half. But Matthews hit a 3 just 0.3 seconds before the buzzer to give the Blazers a 49-48 lead at the break.
Rondo pump-faked to the left and then passed right to Pierce for a 3-pointer that made it 77-72 with 32 seconds left in the third. The Celtics then made it a seven-point game when Garnett, who nearly turned the ball over on a bad dribble, gathered it up and hit a long 2-pointer with 0.7 left on the clock.
Notes
Injured Celtics C/F Jermaine O’Neal told coach Doc Rivers he hoped to begin working out again next week after being out with a sore left knee. O’Neal has played in just seven games this season. … Rivers was named Eastern Conference coach of the month for October/November on Monday. Boston’s 13-4 start tied Orlando for best in the East. … The teams wore red warmups with ribbons to acknowledge National AIDS Day. The coaches wore red ties, and several players also wore ruby red shoes. … Portland center Joel Przybilla missed his third straight game with the flu. … After going just 5-for-18 from 3-point range the night before in a loss at Philadelphia, the Blazers opened the game by making 3 of 4 from beyond the arc.