BOSTON, March 29 (Ticker) -- After a slow start, the Dallas Mavericks showed the Boston Celtics why they're one of the NBA's elite teams, and at 23-12, the team with the best road record in the league.

Michael Finley scored 15 of his 24 points in a dominating third quarter as the Mavericks handed the Celtics their worst loss of the season, 108-82.

Coming off Thursday's tough setback in Minnesota, the Mavs ran Boston off its home floor, leading by as many as 42 points in the fourth quarter while nearly handing the Celtics their largest home loss in club history.

The Mavs trailed, 23-21, after one quarter before outscoring the Celtics by a lopsided 68-28 margin in the middle two periods.

NBA.com highlights from Mavs-Celtics: 56k | 300k

Finley led the third-quarter surge, when the Mavs shot 64 percent (16-of-25) and outscored the Boston, 37-11.

"I am as surprised as anyone with that performance," Dallas coach Don Nelson said. "That was very impressive. We haven't played a quarter like that in a long, long time.

"I don't really know if their was a defense that could stop us. We were on such a roll, had great opportunities, made the extra pass and just shot the lights out."

Dirk Nowitzki had 18 points and 10 rebounds and Raef LaFrentz 14 and 13 for the Mavs, who reached 50 wins for the second straight season while moving one-half game ahead of second-place San Antonio in the Midwest Division.

Paul Pierce had 19 points for Boston, which fell 5 1/2 games behind first-place New Jersey in the Atlantic Division with nine games remaining.

"They flat out whooped us in every phase of the game," Celtics coach Jim O'Brien said. "We didn't have an answer for anything they did and it was like an avalanche in the third quarter."

Starting to fit in after being acquired near the trade deadline, Nick Van Exel gave the Mavericks a lift in the second quarter, when they opened the period on an 18-3 run.

The tempestuous guard scored the final five points of the burst, capped with a long 3-pointer to give Dallas a 39-26 lead. He had 11 of his 13 points in the quarter as the Mavs opened a 52-40 advantage at the break.

Boston struggled miserably from the field in the half, shooting just 32.5 percent (13-of-40).

But it was the third quarter when Dallas took control. Finley started the quarter with a layup and scored seven points in a 9-2 surge that pushed the lead to 61-42.

"We came out and played from the jump ball to the end of the game like we needed to play," Finley said. "I think last night in Minnesota we didn't play the type of ball we wanted to in the first half, and as a result, we lost the game. And we didn't want that to happen, not only tonight, but for the rest of the year."

After the Celtics scored the next four points, the Mavs put the game away with a 24-2 run to take a commanding 86-48 lead with under a minute left in the period.

Greg Buckner drilled a 3-pointer from the left corner as time expired in the quarter, giving Dallas an 89-51 bulge.

Buckner had 11 points and Eduardo Najera 10 for the Mavs, who shot 44 percent (40-of-91) and held a 52-40 rebounding advantage.

The Celtics were showered with boos from the home crowd as they made just 5-of-19 shots from the floor in the period and were outworked on both ends of the floor.

"I thought we kind of put our head down when they went up and made a few tough shots, and that carried over on the offensive end, and it can't be like that," Pierce said.

A jumper by Finley, who made 10-of-20 shots, gave Dallas its largest lead of the contest at 95-53 with just under 11 minutes left.

Boston was able to avert its largest home loss by outscoring the Mavs by 16 points over the last 10:45. The Celtics biggest home loss was a 142-103 defeat to Baltimore on January 9, 1970.