Tanner Roark pitched five innings to get the win in his Oakland debut, and the Athletics beat Adam Wainwright and the St. Louis Cardinals 4-2 on Sunday.
St. Louis fell 1½ games back of NL Central-leading Chicago, which swept Milwaukee with a 7-2 victory.
Paul DeJong homered for the Cardinals, who lost each of their four games against the A’s this season.
Cardinals: RHP Michael Wacha (6-4, 5.15 ERA) returns to the starting rotation against the Dodgers on Monday.