BOSTON — Doc Rivers doesn’t like the way the Celtics are playing right now.

The Celtics coach likes the fact that they are winning games but he says the Celtics believe they can turn it on and off whenever they feel like it.

And there are a lot of teams in the NBA that they can’t do that against. If they do, they will lose, says Rivers.

Fortunately for them, Philadelphia, playing without starting guard Louis Williams (fractured jaw) and forward Elton Brand (hamstring), is not one of those teams.

The Celtics edged the short-handed 76ers, 113-110, on Wednesday night at the Garden, but the game was a lot closer than it should have been.

The 76ers, who the Celtics beat Nov. 3 by 31 points, were up by 52-51 at halftime, and 85-79 after three quarters. It looked like the Celtics were going through the motions while the upset-minded and athletic 76ers were out to avenge their embarrassing loss to the Celtics earlier this month even though they were missing two of their star players.

The sellout crowd of 18,624 was in shock as the Celtics trailed by 3 with just over 10 minutes to go. That’s when the Celtics finally decided to turn it on.

First Paul Pierce (27 points, 6 rebounds, 6 assists) hit a 3-pointer. Then Rasheed Wallace buried a 3 and Rajon Rondo followed that up with a layup. The Celtics opened up the fourth quarter with a 13-2 run, and by the midway point of the quarter, they had their biggest lead of the game up to that point, 100-91.

The 76ers made one last push and slashed Boston’s lead to 107-105 with 1:20 left after two Andre Iguodala (25 points, 9 rebounds, 9 assists) free throws. An Eddie House (13 points) missed a 3-pointer on Boston’s ensuing possession set up a wild finish.

Thaddeus Young (17 points, 6 rebounds) tried to drive to the basket and he was stripped by Rondo, which lined up a Celtics 2-on-1 fast-break scoring opportunity. Ray Allen (18 points, 5 rebounds) missed a layup, however, and Philadelphia was off to the races.

Pierce stood his ground and took a charge on an Iguodala drive, getting the ball back for Boston. The Celtics used the entire shot clock on their ensuing possession, and Rondo knocked down a 17-foot baseline jumper with 9.6 seconds left to make it 109-105.

Iguodala answered with a 3-pointer from the top of the key with four seconds left, and Philadelphia fouled Allen with 3.3 seconds remaining.

Allen calmly walked to the free-throw line and sank both shots to give the Celtics a 3-point lead, and after a timeout, the Celtics fouled Young so that Philadelphia could not heave up a potential game-tying 3-pointer. Young made both free throws to make it a 1-point game with 2.7 seconds left

The 76ers fouled House with 1.8 seconds left and he sank both free throws. The Celtics fouled Jason Kapono (20 points) with 1.4 seconds left on Philadelphia’s final possession. Kapono missed both free throws to end any hopes of a Philadelphia miracle finish.

Rivers wants the Celtics to play the entire 48 minutes like they did in the fourth quarter, but, he says, they have not put together a 48-minute game yet.

“You would love it to be perfect out of the box, but that’s not going to happen,” Rivers said. “We’ve done it in stretches. What’s frustrating is in the last week or so, we looked like we were starting to get it and then we decided to make a u-turn. It won’t be the last time. We’re going to get it and we are going to get it at some point quickly, and then it’s going to go away and then we’ll have to get it back and then the next time it’s better for a longer period of time.”

Part of the reason the Celtics are struggling, Garnett said, is because Rivers has installed new plays and it has taken the Celtics a while to get the hang of them.

“Execution at this point is one of the keys that we’re going to strive for each and every game,” Garnett said. “Doc is going to continue to enforce that and we as players have to continue to try to make that a priority and get better at that. It starts with the mindset. We are getting a lot of new stuff that Doc is trying out on us. It’s stuff that we can handle, but executing it is a different thing. We’re working on it.”

Boston center Kendrick Perkins (12 points, 8 rebounds) said the Celtics were hoping to extend their two-game winning streak through Christmas.

“We’re not where we want to be,” Perkins said. “I wouldn’t say we were struggling. I wouldn’t call an [11-4] record struggling, but I feel like we can improve. I don’t feel like we’re that far away. Obviously the expectations are high. We’re only one game out of first place in the whole NBA, so I feel like we’re on the right track.”

“Starting from our last game we want to try to make a run all the way up to our Christmas game,” Perkins added. “We want to be on the right track, so guys are locked in and focused right now. We just have to stick together.”

Everything started out fine for the Celtics, who made it a point to make the extra pass, sometimes to a fault, early on. The Celtics opened up the game with a 14-9 run and led by 27-23 after one quarter.

But the 76ers, led by Kapono who scored 12 of his 20 points in the second quarter, came storming back and led by as much as 41-34 midway through the second quarter after Young buried a 3-pointer to cap an 18-7 Philadelphia surge.

The Celtics answered with a 15-7 run to go back up by 49-48, but Philadelphia would score four of the game’s next six points to lead by one at halftime.

Willie Green scored 14 of his 18 points in the third quarter, when the 76ers outscored the Celtics by 33-28, but Boston found its rhythm in the fourth.