The Spurs, who have not lost back-to-back games since December 30-31, had a six-game winning streak snapped by New York at home on Tuesday, 105-97.
Tim Duncan, who was questionable before the game with a sprained right ankle, scored 27 points and Tony Parker added 21 for San Antonio, which led by 15 points in the third quarter and nine heading into the fourth quarter.
The Spurs made only 22 of their 35 free-throw attempts. San Antonio is 3 1/2 games behind the Mavericks for the lead in the Midwest Division and Western Conference.
Dallas, which is opening a three-game homestand, has won its last three contests, including a 114-93 triumph over Cleveland on Tuesday.
Finley sat out the second half of the game after straining his left hamstring and is a game-time decision for Thursday’s contest.
The teams split their first two matchups this season, with each winning at home. The Spurs won 111-104 on December 11 before the Mavs won here on February 20, 95-87.
San Antonio has won seven of the last nine meetings between the teams.