Saturday's contest featured the exploits of Oakland's leadoff hitter, Coco Crisp, who went 3-for-4, opening the scoring in the bottom of the first inning with his 10th home run and following up with a single, double and his 30th stolen base of the season.
Crisp and his A's have closed the gap on Texas to three games for the AL West lead after the Rangers lost, 4-3, at Cleveland. Oakland leads the wild card chase by two games over Baltimore, in the #2 slot.
The A's and Red Sox complete their series on Sunday, with Oakland seeking the sweep and ninth straight win.
David Freese was the hitting star for St. Louis, going 3-for-5 with three RBI, including a two-run homer in the top of the second, after the Nationals had forged a 4-0 lead.
Freese also provided the game-winner, his single in the ninth inning plating Allen Craig with the go-ahead run.
Having a solid season, Freese is hitting an even .300, with 18 homers and 74 RBI. The Cardinals are two games behind the Braves, owners of the first wild card, lead the Pirates and Dodgers by 1 1/2 each for the second wild card, and trail the Reds by 8 1/2 in the NL Central.