O'Brien won in his first trip to Philadelphia since he was fired after leading the Sixers to the playoffs in 2004-05, his only season as their coach.
"I found out a long time ago that bitterness is for losers," O'Brien said. "I got on with life very, very quickly and enjoyed the best two years of my life."
O'Brien, a Philadelphia native who played for Saint Joseph's, sat at home the last two years and collected the nearly $8 million owed to him by the Sixers. He hoped for another chance in the NBA and got one with the Pacers, who moved into a tie with New Jersey for the eighth spot in the Eastern Conference standings.
O'Brien downplayed all questions about revenge or gaining satisfaction from sticking another loss on the Sixers -- their eighth in the last 10 games.
"The only thing that changes is that I'm going to be able to see some of my family members," O'Brien said. "I can't generally see them anywhere else but here. That's what's good about coming back to Philadelphia."
But it wasn't enough for the Sixers, who flopped at the free-throw line. While Indiana stretched its lead on 14 3-pointers, the Sixers couldn't seriously make a run because it made just 21 of 34 free throws.
Iguodala went 11-for-13 from the line, but Louis Williams was only 2-for-6 and wasted an otherwise steady 14-point effort.
"We knew their offense pretty well," Iguodala said. "It's the same offense coach O'Brien had when he was here."
The Sixers got as close in the fourth as 106-100 on Iguodala's three-point play with 2 minutes left. Iguodala followed with an airball off the break and the Sixers blew their last chance to rally and threaten the Pacers in the final minute.
Rush scored on a layup and Iguodala missed again on a driving layup to seal the win for the Pacers.
Rush went 10-for-18 from the floor overall and hit five 3s.
"I've been really aggressive and have gotten into a streak in these last couple of games," he said. "My teammates have been looking for me and Coach wants me to be aggressive. It's my kind of game. It gets me up and down in the court in a hurry and shooting 3s."
The Pacers went ahead by 15 early in the third when Foster, Rush and Granger all hit long jumpers on three straight possessions.
Much like they did in the first half when the Sixers went on a long run to chip away at the lead, Philadelphia went on an 11-0 spurt late in the third that cut the lead to 76-74. But the Pacers closed on a 14-5 run.
The Sixers used a 16-0 run to pull ahead 37-35 in the second quarter. Murphy hit a 3 to help Indiana regain lead. Rush and Dunleavy hit 3s on consecutive possessions at the end of the half to give the Pacers a 63-49 lead at the break.
"We need to do a better job as starters coming out and starting the game well," Sixers guard Willie Green said. "Once we got in the hole, it was like we were fighting the whole game."
Rush went 4-for-5 from 3-point range and the Pacers made 10 of 17 in the first half.
The Sixers honored Bobby Jones, the sixth man on their 1983 championship team, at halftime. ... Injured Pacers F Jermaine O'Neal called sitting out the season with a bruised left knee a "worst-case scenario" and refused to put a timetable on his return. The Pacers said he'd be out at least two weeks. ... The start of the game was delayed nearly 10 minutes because the shot clock was not working. Temporary shot clocks were placed on the baselines and the problem was solved in the second half.