Nowitzki netted eight points in the fourth quarter and seven in overtime, as Dallas outscored OKC 17-8 in the extra session.
Despite the loss, Kevin Durant's scoring tear continued with 43 points on 15- of-27 shooting. Durant has now scored at least 25 points in 36 consecutive games, just four shy of Michael Jordan's all-time record of 40 games.
Russell Westbrook, who missed Monday's win over Denver to rest his surgically repaired right knee, returned to the court and tallied 23 points, eight assists and seven boards. The Thunder saw their four-game winning streak come to an end.