BOSTON (AP) — Paul Pierce is a shooter, so he does what shooters do and he thinks the way shooters think.

All the time.

Even after missing his first 10 shots of the night.

“I was getting great shots, man,” he said. “I thought something was wrong with the rim, not with me.”

Pierce shrugged off his shooting slump and scored 16 points in the fourth quarter, including seven straight to put the Boston Celtics ahead for good in a 103-94 victory over the Indiana Pacers on Tuesday night.

Pierce finished with 21 points, going 12 for 13 from the free throw line to make up for his slow start from the floor.

“Shooters believe they can shoot. They always believe it,” Celtics coach Doc Rivers said. “They can go 0 for 20, and they’re thinking the odds are on their side.

“That’s the difference between the average player and the great player. The average player stops shooting and turns it into a bad game. The great players are thinking after every miss, the next one has to go in.”

Kendrick Perkins scored 19 points to go with eight rebounds, and Rasheed Wallace filled in for an ailing Kevin Garnett with nine points and 13 rebounds. Garnett was scratched just before game time with a right thigh bruise, the first game he has missed this season.

“I think everyone was looking around, and saw Kevin was not putting on his uniform,” Pierce said. “This was right before the game. It’s like, ‘Kevin is not playing.’ I guess it took us a half to realize that Kevin wasn’t going to be out there. … It was definitely an adjustment.”

Troy Murphy had 24 points and a season-high 18 rebounds for Indiana, which lost its fourth straight. Earl Watson scored all 18 of his points in the first half to help the Pacers open a 15-point halftime lead.

The Celtics trailed 66-54 before scoring 13 straight points – nine by Ray Allen, taking their first lead of the game on his 3-pointer with 4:45 left in the third quarter.

It was 86-all when Pierce hit a pull-up jumper from the right side for his first basket of the game. He followed with a steal that led to two free throws, and then a 3-pointer that made it 93-86.

After Allen hit from the right side, Pierce hit two more free throws and a jumper for a nine-point lead with 52 seconds left.

“It’s the NBA. You keep shooting,” Pacers guard Dahntay Jones said. “You make one and it gets a lot easier.”

It wasn’t even that unusual for Pierce, who had 48 points in a 2001 game against New Jersey after scoring two points on 1-for-16 shooting in the first half. Rivers said he uses that game as a lesson for his own children.

“It’s a good message,” Rivers said. “Confidence is the key.”

Rivers wasn’t with the Celtics at the time. Their coach: Jim O’Brien, who’s now with the Pacers.

“They have three All-Stars on the court. They’re a very talented team. That’s why they came back,” O’Brien said. “We don’t have any All-Stars.”

Garnett was a late scratch with a thigh bruise after participating in the walkthrough with the team at 5 p.m. Rivers, who made no mention of the injury when he met with reporters at 6:40 p.m., said Garnett was hurt against Memphis on Dec. 14 but told no one except the trainer until Tuesday.

Garnett missed 22 of the last 26 games last season – and all of the playoffs – with strained ligaments in his right knee.

“It was just like last year,” Rivers said. “When Kevin went out last year, we had the ability to score. We just couldn’t stop people from scoring.”

NOTES: The Celtics open a four-game road trip with a Christmas game at Orlando. … Allen was 2 for 8 from 3-point range. … The Pacers are the only team to hand the Celtics a road loss this season. … Watson made his third straight start at point guard in place of T.J. Ford.