Ray Allen followed his 51-point Game 6 performance with 23 on Saturday night, Paul Pierce added 20 and Boston pulled away from Chicago just before the half to finish the Bulls off 109-99 - a rare regulation victory in what might have been be the best first-round playoff series in league history.

"I don't see great. I just see hard," said Celtics coach Doc Rivers, whose team will play the Orlando Magic in Game 1 of the Eastern Conference semifinals on Monday. "For a coach, it's just: Win the series."

Ben Gordon scored 33 and Kirk Hinrich scored 14 of his 16 in the fourth quarter to help Chicago cut it to three points - thanks in part to a bizarre scoring change that added a point to the Bulls' score two hours after a first-half 3-pointer was mistakenly ruled a 2.

Boston made all 11 of its free throws in the last 2 minutes to hold on, and the seventh-seeded Bulls return to Chicago knowing they took the defending champs to the limit - and quite often beyond. The four overtime games was a record for a series, and the seven overtimes total were the most any team has ever played in an entire playoff - and it's just the first round.

"It was a long, grueling series. I thought this was one of the most mentally tough series I've ever been in," Pierce said. "Thank goodness we were battle-tested and we were able to pull this out in seven games. ... We still are the champs until somebody knocks us off."

Kendrick Perkins had 13 rebounds, Rajon Rondo had 11 assists and Eddie House scored 16 points - going 5-for-5 from the floor, including four 3-pointers. Joakim Noah had 15 rebounds for Chicago.

Celtics forward Glen "Big Baby" Davis, who scored 15 as the sub for injured star Kevin Garnett, said he was glad to finish this one off in the regulation 48 minutes.

"Oh, my God. Overtime after overtime after overtime," Davis said. "We did what we had to do to get the job done."

After three consecutive overtime games, the series went from Odyssey to oddity when an unusual scoring correction helped the Bulls cut the deficit to three points in the fourth quarter.

With 5:44 left in the game, the public address announcer said that because of a "technical error" Gordon was credited with a 2-pointer instead of a 3-pointer, apparently on his basket with 8:32 left in the first quarter. Officials can use video replay to check whether a shot is from beyond the arc or not, but it is supposed to come at the first break after the basket - not three quarters later.

Gordon's shot had been reviewed at the break that came with 3:37 left in the first, the scoresheet said.

The change made the Celtics' lead 89-84, then Gordon hit a pair of free throws. Perkins followed with a layup and then traded free throws with Gordon before Eddie House hit a 3-pointer to make it 96-88 with 2:30 left.

The Celtics made 11 straight free throws from there - one of them on a three-point play by Allen that made it 105-97 with 37 seconds left.

Bulls point guard Derrick Rose scored 18 with three assists, failing to follow up on his Game 1 playoff debut in which he scored 36 points with 11 rebounds. The NBA rookie of the year averaged just 12.7 points and 4.2 assists in the four Chicago losses.

"We had a lot of young guys who went through it for the first time. I think that will help us in the future," said Bulls coach Vinny Del Negro, himself a rookie. "Whenever you can go through an experience like this, I think it's only going to make you better. Knowing how the level of physicality goes up, knowing how playoff basketball is played. ... It's a great learning experience for us."

Chicago led by as many as nine points, 32-23, after Gordon scored the first five points of the second quarter - giving him 17 at that point. The Bulls took a 36-30 lead with 8:01 left in the half before Boston scored the next 11 points and 20 of the next 22 to go into the break with a 14-point lead.

Chicago had eight turnovers and missed four free throws during the stretch.

Notes: It was the first Game 7 for the Celtics since last year's second-round series against Cleveland, when Pierce and Cavaliers forward LeBron James combined to score 86 points and Boston won to advance to the Eastern Conference finals. ... Celtics coach Doc Rivers before the game mocked reports that Kevin Garnett would return. "You guys have said it all the last few days. I thought someone was going to report they saw Bigfoot and Sasquatch." ... Celebrities in the crowd: Actor Bill Murray and David Axelrod, a senior adviser to President Barack Obama.