Nowitzki and Jason Terry scored 18 points apiece and the surging Mavericks rolled to a 106-91 victory Friday night over the Suns.
"The game changed without Nash," Mavericks coach Rick Carlisle said. "He's one of the best players ever. He was aggressive and was going to have a major impact on the game."
Caron Butler added 17 points, Shawn Marion had 15 and Tyson Chandler pulled down 12 rebounds for the Mavericks, who have won 14 of 15.
Nash missed the final three quarters with a neck injury. The All-Star point guard said he lost feeling in his extremities for a brief time after hitting the floor with 7:17 left in the first.
Nash and Chandler collided while going for a loose ball in the Phoenix backcourt. Nash fell on his neck and was down for several minutes before walking slowly to the bench.
After the game, Nash said he should be fine, pending the results of further tests. But the collision still gave Nash and his teammates cause for concern.
"I just bumped my head at a weird angle and had a spinal cord situation and lost feeling in my arms and legs," Nash said. "There was 10 seconds there where it was really scary, but it came back. They just felt like it wasn't worth risking it tonight. We'll see how it goes tomorrow, but I'm optimistic that the amount I've improved already, hopefully I'll improve enough to play Sunday or Monday."
Nash, who started the night averaging 18.1 points and 10.6 assists per game, finished with four points and one assist.
"Obviously, it changes everything that we do," Phoenix coach Alvin Gentry said. "We couldn't make shots, and I don't want to take anything away from (the Mavericks) because they're a good defensive team. They've proven that."
Phoenix started the night averaging a league-high 109 points per game. Dallas was holding opponents to 93.2 per game. Only five NBA teams were better defensively.
"Our goal every night is to play the best defense we can," Carlisle said. "But without Nash, the numbers are going to be skewed."
Hakim Warrick had 15 points and 14 rebounds and Goran Dragic added 14 points and 10 assists for the Suns, who have lost four of five.
Butler's seven points paced a 22-6 run from the end of the second quarter through the early part of the third as the Mavs expanded their advantage to 70-48 with 5:58 left in the third.
Dallas took an 80-59 lead into the fourth quarter, with Phoenix going 7 for 24 from the floor in the third.
The Mavericks wasted first-half leads of 17 or more points in their previous three games, winning twice.
Not this time. Dallas led by as many as 24 in the third and never let its advantage slip to fewer than 12 points in the final quarter.
"We've got to put teams away," Terry said. "We've let teams hang around. It's come back to bite us."
The Mavs built a 54-42 halftime lead behind Terry's 16 points and Marion's 15. Nowitzki committed three first-half fouls and had only four points at the break.
Nowitzki is 36 points short of matching Larry Bird's total of 21,791, which is 25th on the career list.
"Obviously, that's unbelievable to me, and I really don't know what to say," Nowitzki said. "If someone would have told me that 12 years ago when I came into the league, I would have said they were out of their minds."
Notes: Dallas completed a 5-1 homestand. ... The Mavs have won the last six at home against the Suns and seven of nine overall. ... The game was held up for about five minutes following a timeout in the second quarter when plastic debris from a holiday promotion littered midcourt. Several arena workers had problems sweeping up the clingy material. ... Phoenix C Robin Lopez had six points in his second game back since missing 14 with a sprained left knee. ... Suns F Channing Frye fouled out with 3:50 left, finishing with eight points and 14 rebounds. ... The Suns fouled Mavericks C Brendan Haywood intentionally three times in the fourth quarter. Haywood missed five of six free throws before he was replaced by C Ian Mahinmi. The Suns tried fouling Mahinmi, who made four straight from the line.