Nowitzki scored 25 points, including the go-ahead jumper with less than 20 seconds to play, and the Dallas Mavericks snapped Boston's five-game winning streak with a 89-87 victory over the Celtics on Monday night.
Jason Terry added 17 points, and Tyson Chandler had 12 points and 13 rebounds for Dallas.
On Saturday night, Nowitzki played poorly, going scoreless in the fourth quarter and committing seven turnovers in a home loss to Denver.
He had his longish blond hair cropped into a buzz cut during the day on Monday, then helped his team grind out a win over one of the league's elite teams.
"Dirk cut his hair," Terry said. "He's back to his MVP status. Tonight, he wasn't going to settle."
Paul Pierce scored 24 points, Kevin Garnett had 18 points and 15 rebounds, and Rajon Rondo added 11 points and 15 assists for the Celtics, who'd won their last three trips to Dallas.
Boston held an 87-82 lead with 1:58 left on Pierce's 17-footer. But Nowitzki converted a layup, then Terry made a 3-pointer with 1:13 remaining to tie it at 87. Garnett missed an inside shot with 36 seconds left, and Jason Kidd passed to Nowitzki, who connected from 16 feet on the left wing over Boston's Glen Davis with 17.4 to play to give Dallas the lead for good.
"I knew Kidd was going to find me and then Davis was there," said Nowitzki, who had 10 points in the fourth quarter. "I was able to face him up and knock the shot down."
Rondo missed a 3-pointer with 3.8 seconds left, but Terry fouled going for a loose ball to give the Celts another possession. Garnett's desperation 3-pointer from the right corner failed to hit the rim.
Boston coach Doc Rivers was looking for a better shot than what the Celtics got, calling it "a terrible play."
"I hope I can draw up a better play than that," Rivers said.
Terry's 3-pointer in the final two minutes was another key basket for the Mavericks. A pass from Kidd, who finished with 10 assists, set up Terry.
"I told Jason that if he got in the lane, look for me because they were leaving me alone," Terry said. "He must have eyes in the back of his head."
Dallas finished the third with a 7-2 run for a 70-69 edge heading into the final quarter, but the Celtics went 8 for 21 from the field in the final quarter.
"It was a game we just let slip away," Pierce said.
Midway through the second quarter, Terry swished a 3-pointer from deep in the left corner that he had to loft high over Marquis Daniels of the Celtics. Terry high-fived a fan, Daniels was whistled for a foul on the shot, and Terry connected on a free throw for a four-point play to give Dallas a 40-30 lead.
Dallas carried a 50-40 lead into halftime behind Chandler's 10 points and nine rebounds.
Celtics center Jermaine O'Neal missed the second half with a sore left knee. O'Neal started and played 11 minutes in the first half, contributing two points and three rebounds.
O'Neal said he had "no explosion" during the game and decided that the Celtics would be better off with him on the bench.
The Mavericks were still reeling from Saturday night's 103-92 defeat to Denver, their second loss in three home games.
In that game, Dallas had 21 turnovers, eight in the final quarter.
"That last loss hurt," Chandler said. "I was up until 4 in the morning, recapping that game. Tonight I wanted to lift the team with my play."
This time, the Mavericks were better on the defensive end, holding Boston to 38 of 91 shooting (41.8 percent).
"Our defense was big," Nowitzki said. "We contested every shot down the stretch. This was a great win at home against one of the best teams in the league, a big physical team. They're a handful."
This program aired on November 9, 2010. The audio for this program is not available.