Gary Neal sparked the Spurs with 21 points and outside shooting off the bench to help San Antonio earn its 13th win in 14 games and improve its franchise-best start to 28-4.
Playing in his first season in the NBA, the 26-year-old Neal spent the last few years playing overseas including stints in Italy and Spain before arriving in San Antonio.
"Overseas was great for me. Playing there for three years, getting confidence and experience (allowed me) to be able to make shots and be comfortable to help (the Spurs)," Neal told reporters, having provided the Spurs with extra perimeter scoring this season.
Neal made five of his team's 11 three-pointers on the night while Tim Duncan put in 17 points and grabbed 11 rebounds to help a balanced effort.
In a showdown between the two top teams in the Western Conference, Nowitzki sat out his second straight game with a sprained right knee.
Nowitzki was injured against the Oklahoma City Thunder on Monday and is listed as day-to-day.
"The knee was giving me a little trouble two weeks before," Nowitzki said.
"It feels pretty good. It's already better than it was two days ago. Maybe this weekend, maybe early next week... that's what I'm looking at (for a return)." Without their leading scorer, Dallas (24-7) got a team-high 30 points from Caron Butler to stay within striking distance but were unable to overhaul the Spurs in the closing minutes.
San Antonio made three straight three-pointers midway through the fourth to go ahead by 10 and held on from there.
The Mavericks trailed by as much as 16 in the second quarter but the cut the deficit all the way down to one in the third.
Jason Kidd recorded a triple-double with 12 points, 13 assists and 10 rebounds but could not keep Dallas from dropping its second straight game.
