Putting together a five-game winning streak and getting 10 games above .500 were once common achievements for the Dallas Mavericks.

Now, both are season highs as Dallas slowly works its way back into playoff contention in the Western Conference.

Dirk Nowitzki scored 20 points, Shawn Marion finished with 11 points and 10 rebounds, and the Mavericks beat the Boston Celtics 102-91 Sunday night to extend their winning streak to five straight.

“There are encouraging signs, but there’s no way we can exhale or start feeling good,” coach Rick Carlisle said.

Jose Calderon added 18 points and Monta Ellis played through a sore hamstring and scored 11 for Dallas, which won for the sixth time in seven games and pulled 10 games above .500 for the first time this season at 31-21.

“We’re looking to move up,” Nowitzki said. “If you look at the standings, (places) five through eight is only separated by a couple of games. We’d love to keep pushing.”

Vince Carter scored 14, Devin Harris had 12 points and Samuel Dalembert grabbed 11 rebounds for Dallas. The Mavericks led by six at halftime and pulled away in the third quarter by outscoring the Celtics 28-18.

“The third quarter and the start of the fourth killed us and took us out of the game,” Boston coach Brad Stevens said.

Rajon Rondo had 15 points, 12 assists and eight rebounds for Boston, which had won three straight games.

Jeff Green scored 18 and Jared Sullinger had 11 points and 12 rebounds for the Celtics.

Boston managed to stay close through the first half despite shooting 27 percent, then Dallas took command early in the third quarter and pulled ahead by as many as 24 points before the Celtics rallied when it was too late.

“We still kept it close. That was the beauty of it,” Sullinger said. “We played hard, but they just got away and the deficit was so big we couldn’t dig ourselves out of that hole.”

The Mavericks opened the second half on a 16-5 run, holding the Celtics to two field goals through the first 6:29 of the third quarter. A 3-pointer by Green got Boston within 53-43, but Calderon answered from beyond the arc and Marion and Dalembert followed with layups to extend the Mavericks’ lead to 60-43.

“In the third quarter, we were doing the same kind of defense, but now we were sharing the ball and making open shots and that’s what the difference was,” Calderon said.

Boston’s only scoring run in the period was a 4-0 spurt late on layups by Kris Humphries and Kelly Olynyk, which Dallas negated in the last minute on two foul shots by Harris and an alley-oop from Harris to Brandan Wright with 5 seconds remaining to give the Mavericks a 72-56 lead entering the fourth.

Wright opened the fourth with another alley-oop from Carter, who added a layup for Dallas’ eighth point in a row and the Mavericks’ lead was up to 76-56.

The Celtics put together a late run to make it close down the stretch before running out of time. Rondo and Green hit back-to-back 3-pointers to pull Boston within 96-84 with 2:25 remaining.

Johnson added another 3-pointer with 1:18 to get the Celtics within 98-89, but Calderon hit a layup to put the Mavericks back up by double-digits.

NOTES: Olynyk finished with 14 points and Humphries scored 10 for Boston. … Marion got his seventh double-double of the season. … The Mavericks had one other four-game winning streak this season, but had reached five beating Utah on Friday and Boston on Sunday. … Rondo was the only Boston starter to make more than two field goals in the first half with four. … Nowitzki scored 15 in the first half. … The Celtics shot 27 percent (13 for 48) in the first half and opened the third quarter 2 for 10.

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