"It shows how hard we've worked to get back," said Iguodala, who finished with 28 points. "But I think we still have to have that mentality like we're a team that's still under .500 and still fighting. It's not over yet. We've gotten to a point where we want to be, which is over .500, but we still don't have an 'X' by our name" to signify a playoff berth.
Eddie House's 3-pointer gave Boston an 80-69 lead with 8:20 to play, but the Celtics didn't score again until Pierce hit a free throw with 1:38 left. By that time, the Sixers were on their way to their 18th win in 23 tries, improving their record to 36-35 and moving them into postseason contention.
"They are making a good run at the playoffs over the last month and a half," Celtics forward Paul Pierce said. "They will be a dangerous team in the playoffs."
The Sixers won just five of their first 18 games and sat 18-30 seven weeks ago. But with Monday's win, they pulled ahead of Toronto and into sixth place in the Eastern Conference, a game behind fifth-place Washington.
Beating the top team in the NBA also gave them a jolt of confidence.
"It's huge when you come in here and win a game like this against Boston, it does a lot for us," coach Maurice Cheeks said. "We still have a long way to go. This is just one step to try and get to where we want to be."
Andre Miller scored 20, Thaddeus Young had 16 points and nine rebounds, and Samuel Dalembert grabbed 12 boards for Philadelphia.
Kevin Garnett scored 18, Leon Powe had 16 and Ray Allen scored 14 for Boston, which lost its second straight after winning 14 out of 15. The Celtics long ago clinched a playoff berth, and they played as if it didn't matter down the stretch.
"These games are crucial to us, too," Garnett said. "We are trying to establish something, and a rhythm going into the playoffs. So these are big games for us, too, just as it is for all the other teams coming in here."
Boston never trailed in the first quarter and led for all but a few minutes of the second. But it was tied at 66 near the end of the third before House hit a 3-pointer, and Glen Davis made a couple of free throws to give the Celtics a five-point lead after three.
House hit another 3 early in the fourth to make it 78-68, and he added a left-side jumper to give the Celtics an 80-69 lead with 8:20 left. The Sixers scored the next 19 points - five by Young, four by Louis Williams and a steal and emphatic breakaway dunk by Iguodala to tie it.
Iguodala finished off another fast break to give the Sixers an 82-80 lead, then hit one of two free throws, another steal-and-dunk, another free throw and a fallaway jumper to make it 88-80.
Notes:
Powe had 12 points and five rebounds off the bench in the first half for the Celtics. Pierce was 3-for-4 from 3-point range. ... The first half ended 52-48 after a controversial goaltending call on Garnett on Reggie Evans' shot from the lane. Celtics coach Doc Rivers was livid. ... It was Boston's first game back since a five-game road trip in which it went 4-1, including the first sweep of the Texas Triangle - San Antonio, Houston and Dallas - since 1987. ... Three-hundred members of the U.S. military attended the game, compliments of fans who donated tickets, and were recognized with a standing ovation by the crowd and some of the players. One member of the U.S. Navy, Wymon J. Anderson, won $5,000 worth of vision correction surgery when he hit a free throw and a 3-pointer - blindfolded. ... James Posey missed the game to attend to a family matter, but is expected to be back for Wednesday's game against Phoenix.
