PHILADELPHIA, April 7 (Ticker) -- A strong finish by Paul Pierce put a serious crimp in the Philadelphia 76ers' playoff hopes.

Pierce scored 33 points and grabbed 12 rebounds and rookie Gerald Green added a career-high 17 points to lead the Boston Celtics to a 109-99 victory over the 76ers.

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Boston won for the third time in four meetings against Philadelphia (34-41), which remains in ninth place in the Eastern Conference, one game behind Chicago, which it plays on Saturday.

"I'm always thinking that something good is going to happen," Sixers coach Maurice Cheeks said. "I think if you go in there thinking, 'Yeah, you're going to get beat by 20,' there's no sense of us going. There's no sense of us getting on the plane and going to Chicago and giving us a chance."

After Chris Webber made two free throws to give Philadelphia a 76-69 lead with 4:07 left in the third quarter, Boston scored the next 15 points, all on baskets from the arc.

Raef LaFrentz opened the burst with consecutive 3-pointers, Green added another and Pierce closed the run with two more as the Celtics took an 84-76 edge in the first minute of the fourth quarter.

"This team has not been a team that has packed it in all year long," Pierce said. "We got a lot of guys who want to finish the season on a strong note so that we can look forward to something next year."

"Tonight was good because it was against a team that had to win," Celtics coach Doc Rivers said. "When we got down, we could have gone the other way. It was a conscious choice by our guys to stay in the game. I was really proud of them."

Allen Iverson made two straight baskets to give the 76ers a 91-88 lead with 6:18 to play before the Celtics closed with a 21-8 spurt. Pierce scored nine points, Green nailed a 3-pointer and rookie Ryan Gomes converted a three-point play with 2:34 to go.

"We knew that they were going to make their run," Pierce said. "We were able to keep it close until I was able to do what I had to do get my team over the top."

"The guys told me to stay aggressive and that's what I tried to do," Green said. "I started to get focused and get ready to play. I've been going out there, playing hard and being more aggressive. That's been the biggest change."

Tony Allen scored 16 points, LaFrentz added 12 and Delonte West had a career-high 12 assists for the Celtics, who shot nearly 53 percent (39-of-74) from the floor.

"I thought we changed the game and we went small with four smalls and one big," Rivers said. "It allowed us to stretch the floor, and pick-and-roll. Whoever it was, the key was we kept moving the ball."

Iverson made 14-of-25 shots en route to 37 points and Webber added 18 with 11 rebounds for the 76ers, who have lost three straight games.

"As a group, we are not playing hard enough to win basketball games," Iverson said. "We don't seem hungry. We don't seem like we want to make it to the playoffs. It's frustrating for me because I owe that to my teammates, to be one of those guys that goes out there and plays hard every night. I just expect the same in return from them."

"If you really have fear, you play a little harder than we did and we didn't play that way," 76ers forward Kyle Korver said. "It seems like we're a step slow. We're not the most athletic team, so we have to me more aggressive. We've gone over everything we can think of why we don't finish off games, but we don't and tonight was just another case of that."