Mark Aguirre put Dallas ahead with an eight-foot turnaround jumper with 2:18 to play in overtime and the Mavericks went on to defeat visiting Atlanta.
Atlanta rookie Kevin Willis sent the game into overtime with a layup after rebounding his own miss from in close.
After Aguirre, who scored 30 points, put Dallas ahead, the Mavericks got the ball back when Atlanta's Sly Williams missed two free throws.
Aguirre followed with a 19-footer on the next possession to give Dallas (4-4) a three-point lead it never lost.
Brad Davis and Jay Vincent sank six free throws down the stretch for Dallas as Atlanta (2-5) was forced to foul.
Rolando Blackman scored 30 points and Vincent had 20 for Dallas, which led, 95-91, with seven seconds left in regulation.
Willis made a three-point shot to pull Atlanta within one with five seconds left.
Davis, who had made 16 straight free throws this year, missed one of two before Willis took a full-court pass and put up a shot from 17 feet that missed.
Dominique Wilkins, who finished with 15 points to go with Williams' 22, put Atlanta ahead for the last time at 103-102 with a free throw with 2:33 left in overtime.