updated 10:50 p.m. ET Dec. 7, 2008

INDIANAPOLIS - The struggling Indiana Pacers have caused the most headaches for the nearly invincible Boston Celtics this season.

The Celtics beat the Pacers 122-117 in overtime on Sunday to win their 12th straight game, but not before nearly losing to Indiana for what would have been the second time this season. The Pacers beat Boston 95-79 in their home opener.

The Celtics needed all of Ray Allen’s season-high 35 points to avoid another embarrassing loss at Conseco Fieldhouse. Allen made 13 of 21 shots, including seven of 12 3-pointers. He said the Pacers are better than their 7-13 record.

“I think the Pacers are a real good team,” Allen said. “I don’t look down on them as a team that can’t compete. Regardless of what their record is, they’re a good team.”

Kevin Garnett had 17 points, 20 rebounds and five steals, Paul Pierce had 17 points and eight rebounds and Eddie House had 15 points for Boston (20-2). The Celtics are on their longest win streak since 1986, when they won 14 straight in a championship season.

Marquis Daniels led Indiana with a season-high 26 points. Danny Granger scored 20 points, but shot just 7-of-22 from the field.

Indiana is one of two teams to beat Boston this season, and the Pacers nearly pulled it off again by shooting 50 percent from the field against the league’s top defensive team. It was the most points the Celtics have allowed this season.

But it was another case of Indiana failing to close the deal. Three of Indiana’s past eight losses have come in overtime.

“We’ve been in so many of these close games and we struggle to finish,” Granger said. “It’s a learning experience for us. We haven’t been in this situation too much.”

Boston defeated Indiana 114-96 on Wednesday. Rajon Rondo had a triple-double with 16 points, 13 rebounds and 17 assists that night, but had only seven points, seven rebounds and six assists on Sunday.

It was an unusually close call for the Celtics. They had won their previous 11 games by an average of 14 points.

In this case, Boston’s best players overwhelmed the Pacers in clutch situations. Boston coach Doc Rivers said the Celtics stole a victory.

“That’s what good teams try to do,” Pierce said. “We try to find ways to win. It’s not going to be pretty every night, but whenever you can find a way, especially the way things were going tonight, we’ll take it.”

The Pacers trailed 111-108 in overtime before Rasho Nesterovic scored and was fouled. He missed the free throw, and Boston maintained its lead.

Rondo scored on a floater to make it 113-110, but Indiana’s Jarrett Jack made one of two free throws with 1:13 left in the extra period to trim Boston’s lead to 113-111.

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Allen curled around a screen and made a 3-pointer from beyond the top of the key with the shot clock winding down to make it 116-111 with 43 seconds left. Indiana’s T.J. Ford made a 3-pointer to make it 118-115 with 22.8 seconds to go, but the Celtics went 4-for-4 from the free-throw line the rest of the way.

Jack was fouled with 14.4 seconds left in regulation and made both free throws to give Indiana a 105-102 edge. Allen missed a quick 3-point shot, but House rebounded and got the ball to Pierce, whose 3-pointer from the left wing tied the game with 7.5 seconds left.

“It wasn’t really by design,” Pierce said. “It was for Ray or Eddie coming off. Ray missed the shot, and we just kept scrambling. Eddie gets the offensive rebound and finds me wide open, and I got an opportunity to tie it.”

Jack missed a long jumper from the right corner, and Garnett rebounded and called timeout with 0.8 seconds left. Rondo threw the inbounds pass away, giving the Pacers one last shot in regulation. Jack missed an open jumper from virtually the same spot as before, and the game went to overtime.

“We had control down the stretch, we were one rebound away from the win,” Granger said. “We could have beat them twice in three times we played them, but we just let it get away.”

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