Garnett puts finishing touch on Clippers

Kevin Garnett couldn’t help but smile, a sure sign that he’s feeling healthy.

Ray Allen scored 20 points and the Boston Celtics, sparked by an alley-oop dunk from Garnett, pulled away for a 90-77 win over the Clippers on Monday night.

Garnett played 18 minutes, making all five field-goal attempts while scoring 12 points. He added two rebounds and two assists in his third game back since sitting out 13 because of a sprained right knee. He left a few minutes after scoring on an alley-oop pass from Rajon Rondo -- a similar play to the one in which he hurt his knee against Utah on Feb 19 -- but was fine.

Boston trailed, 55-52, midway through the third quarter before scoring 14 straight points to take control. The Celtics took the lead for good at 56-55 on Garnett’s short jumper in the lane before his alley-oop brought the relatively quiet crowd to its feet.

“The reason I was laughing is because it was such a long time since I had one from so far out, but it felt good,” Garnett said. “I’m trying to give Paul [Pierce] and Ray all I have so far until I get back.”

After Garnett’s dunk, Allen scored on a breakaway layup before he made a three-pointer from the left corner 36 seconds before Pierce’s three from the top, closing the spree.

“We have such a great chemistry when our starting five is out there,” Pierce said. “We don’t like him on the bench. We like him on the floor.”

Rondo had 14 points and seven assists, and Kendrick Perkins scored 12 points and had 13 rebounds for Boston (54-18). The Celtics have a one-game lead over Orlando for second place in the Eastern Conference. The teams meet in Florida tonight.

But it was Garnett’s alley-oop dunk midway into the third quarter that had to make his teammates feel great.

“He has that presence,” Boston reserve forward Mikki Moore said.

Added Stephon Marbury, a teammate of Garnett’s in Minnesota: “He just changes the complexity of the game.”

Zach Randolph led the Clippers with 17 points and 14 rebounds, and Baron Davis had 13 points, eight assists and seven boards.

“He didn’t really get a lot of minutes tonight, but the guys coming off the bench seemed to be playing inspired basketball,” Clippers center Marcus Camby said about Garnett’s time on the court.

Boston led 70-60 after three and pushed it to 83-65 when Glen Davis broke out on a fastbreak and dribbled behind his back before passing to Eddie House, who made a three-pointer with 7:01 to play.

“If you don’t get numbers [on the defensive end], Ray Allen’s going to knock down shots on you, Eddie House is going to make shots on you, and it’s going to be difficult,” Clippers Coach Mike Dunleavy said.

The Celtics led 31-18 after one quarter, but poor shooting by their bench allowed the Clippers to climb right back. Boston’s reserves shot two for 12 in the opening half.