BOSTON - Rajon Rondo knows he isn’t going to outjump Dirk Nowitzki. So the 6-foot-1 Celtics point guard had to outthink him.

Rondo had a season-high 12 rebounds, swiping the ball from Nowitzki and putting in a reverse layup with 42 seconds left to give the Celtics the lead, and Boston held on to beat the Dallas Mavericks 96-90 on Thursday night.

“He didn’t block me out, so I went up under and got the ball,” Rondo said. “I just wanted to get it up quickly before the defense recognized that I had the ball.”

Playing without Kevin Garnett for the third straight game, Paul Pierce and Ray Allen scored 26 points apiece to help the Celtics remain unbeaten against the Western Conference. And they did it against one of the West’s best teams while overcoming 31 points and 11 rebounds from Nowitzki.

Nowitzki, who along with Pierce was picked as an All-Star reserve about an hour before the game, made a pair of free throws with 58 seconds left to tie it at 90. The Celtics got the ball to Pierce, but his shot went around the rim and out.

Along came Rondo to grab the ball away from Nowitzki and put in the game-winner.

“I had the rebound in my hand,” Nowitzki said, “and then Rondo came out of nowhere and snuck it up to the basket before I could react.”

A miss and an offensive rebound gave the Mavericks the ball out of bounds with 17 seconds left, but Jason Terry’s runner was altered to avoid a blocked shot and James Posey came down with the rebound. Posey hit two foul shots, then tipped the ball away from Terry at halfcourt in the closing seconds to ice it.

“Any game we win without Kevin is important for us, part of our growth process,” Celtics coach Doc Rivers said. “Dallas is a team that we are still trying to catch, in our minds. They’ve been there. So when we play those types of teams, they’re important.”

The nationally televised game between two of the NBA’s top teams drew the usual collection of celebrities at courtside, including Red Sox players Jonathan Papelbon and Coco Crisp. Celtics Hall of Famer Bill Russell got a big cheer when he took his seat near the Mavericks bench.

No players from the New England Patriots this time, though: They’re down in Arizona preparing for Sunday’s Super Bowl against the New York Giants.

The Celtics had lost two of their last four and five of their last 11 since opening the season 29-3 to earn Rivers the honor of coaching the Eastern Conference at the Feb. 17 All-Star game in New Orleans. Dallas’ loss deprived Mavericks coach Avery Johnson of the chance to coach the West, which instead went to the Hornets’ Byron Scott.

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Pierce and Nowitzki will meet again at the All-Star game, but both seemed more disappointed that their teammates — Allen and Josh Howard — didn’t make the list.

The two snubbed players seemed to come out with extra motivation. Allen scored 15 in the first quarter, and Howard had 13 — each more than half his team’s points.

But in the second half, Pierce and Nowitzki showed why they were selected. Nowitzki scored 17 in the third quarter and Pierce had 13 as the teams settled into a back-and-forth game befitting a matchup of two of the league’s best.

The Celtics scored eight straight points to take a 58-48 lead with 7:16 left in the third quarter, but the Mavericks erased it with 11 points in a row. Nowitzki fed Terry for a jumper, then hit one of his own; Terry stole the ball on a bad pass by Pierce, and Devean George hit a 3-pointer before Nowitzki made a pair of baskets to give Dallas a 59-58 lead.

In the last 4:10 of the third, there were six lead changes, with Boston taking a 71-70 lead on two free throws by Pierce in with 5.3 seconds left.

Notes: Howard finished with 19 points. ... Rondo had 14 points and four assists. His career high for rebounds is 14. ... Brian Scalabrine, starting in place of Garnett, did not score. ... Nowitzki and Terry had six assists apiece.