PHILADELPHIA -- With the division lead at stake, the 76ers dominated like a team that deserved to stay in first.
The Boston Celtics were more concerned about a teammate than the standings.
The Celtics would have grabbed first with a win, knocking out a Sixers team that has held that spot for all but a few days this season. The Sixers outscored Boston by 20 points in the third quarter to take control.
There was a serious scare when Celtics guard Mickael Pietrus left on a stretcher and was sent to the hospital after an awkward collision late in the first half. He was listed as having a questionable closed head injury. Pietrus landed hard on his tailbone, and his head nearly smacked the court. He instantly clutched the back of his head with both hands and rolled over on his side.
Coach Doc Rivers said Pietrus had X-rays and an MRI. Pietrus also was scheduled for an MRI on Friday night, but the team said he will not be admitted to the hospital. Pietrus will spend the night in Philadelphia and be re-evaluated Saturday.
The Sixers wore down a Celtics team concerned about its injured teammate and already playing short-handed. Pietrus started in place of Ray Allen, who sat out with a sore left ankle. Guard Avery Bradley also left Boston's eighth straight road game with a sprained left ankle.
"I thought the injury, fatigue, everything, kind of all caught up to us," Rivers said.
But it was Pietrus, more than the score, that left the Celtics solemn on the bench. He crashed to the court after he collided with 76ers guard Lou Williams on a drive down the lane, grabbed his head and was down for at least 10 minutes. Trainers from both teams tended to him.
The Celtics circled Pietrus, and a couple of players took a knee as the swingman was put on a stretcher and taken out. Several Celtics sat on the bench with their heads bowed.
"It looked awful," Rivers said. "I just saw his neck snap. You knew that was bad. He was throwing up on the floor, so that's not very good either."
His injury sucked the festive atmosphere in the important game right out of the arena. The Celtics were only a half-game behind the 76ers. Kevin Garnett and Paul Pierce each scored 20 points. Rajon Rondo had 17 assists.
"We shouldn't lose that way," Pierce said. "It was a huge game for us, and we took a step back today."
Williams scored 11 of his 19 points in the fourth quarter. Jrue Holiday had 15 and Andre Iguodala 14 to give coach Doug Collins his 400th career victory. He's the 40th coach in NBA history to hit that total.
"My grandson got up from his nap today, and he was in the bathroom," Collins said, choking back tears, "and [Collins' daughter] heard him in there praying that Pop-Pop could get his 400th win tonight."
The Sixers, who had lost four of five, reverted to their early season form in the third with an absolutely dominant effort. Led by a resurgent Brand, the Sixers used an 11-0 run to take the lead for good. Brand made seven of 10 shots and scored 14 points in the period -- he had only three baskets and six points in the first half.
"When we were winning, they didn't need a lot," early this season, Brand said. "I said, when they need me, I'd be prepared. That was a game like tonight. They needed me to step up and I did."
Brand walked off to a loud ovation when he was subbed out late in the quarter. The Sixers shot 65 percent (15-of-23) in the third, the highlight coming on a sweet alley-oop from Iguodala to Williams for a 78-66 lead.
"I can't say enough these Sixers," Eagles QB Michael Vick posted on Twitter.
If the Celtics can't overtake the Sixers, they can point to their past two games in Philadelphia as a key reason. The Sixers thumped the Celtics 103-71 on March 7. The Sixers topped 94 points for only the second time in six games.
"We look forward to meeting them one more time," Iguodala said.
Rondo had 10 assists in the first half, and Garnett scored 14 points to help Boston lead 49-43. The Celtics made 10 of their first 15 shots and led by as many as 10 points.
The Sixers got a boost when part-owner Will Smith arrived to a boisterous ovation in the second quarter. He stood on his chair, doffed his 76ers cap toward the crowd and pointed at the fans in his second game this week. With the "Fresh Prince" cheering them on, the Sixers went on an 8-0 run and tied the game at 38-all.
Smith congratulated Collins on No. 400.
"This is absolutely ridiculous, to be here for Coach, and an owner of my hometown team, and sitting on the floor," Smith said. "We beat Boston. Larry Bird ruined my childhood, so this is fantastic. So Coach, congratulations, and I'm happy to be here."
Rivers said his son, Austin, has not made a decision yet about leaving Duke for the NBA or returning for his sophomore season. "He's got to make a decision. He leans one way one day, then the other," Rivers said. ... The Sixers are 7-12 after a 20-9 start. ... The Celtics went 4-4 on their road trip. ... Collins has 68 wins with the Sixers.
Information from The Associated Press and ESPNBoston.com's Chris Forsberg was used in this report.