Cubs 7, Cardinals 6: Luis Valbuena scored three times and hit a go-ahead two-run homer in the seventh inning as Chicago opened up a three-game set at home with a wild win over St. Louis.

After Cardinals pinch hitter Oscar Taveras broke a 5-5 tie with a pinch-hit RBI single in the sixth, Kevin Siegrist (1-2) hit Anthony Rizzo with a pitch to begin the seventh. Valbuena lifted a high fastball into the seats in center two batters later to put the Cubs in front while Neil Ramirez stranded the tying run at third in the eighth and Hector Rondon worked around a one-out single in the ninth for his 12th save.

Justin Grimm (3-2) worked a scoreless seventh to get the decision while Ryan Sweeney added a three-run homer and finished with a season-high four RBIs for the Cubs, who won for only the second time in seven tries since the All-Star break. Matt Carpenter and Matt Holliday homered as St. Louis has dropped four in a row for the first time since last August.

Carpenter and Holliday singled in the first and the Cardinals scored three unearned runs in the opening frame when Chicago second baseman Arismendy Alcantara’s throwing error on Matt Adams’ grounder allowed Carpenter to score. Jon Jay took advantage of another miscue later in the frame, plating two with a two-out double when left fielder Chris Coghlan was unable to field the ball cleanly.

Sweeney evened it with a three-run shot in the second and gave Chicago its first lead one inning later with a two-out single before Cubs starter Travis Wood led off the fourth with his ninth career homer. Wood could not hold the two-run advantage, however, as Carpenter and Holliday tied it up with solo blasts in the fifth.

GAME NOTEBOOK: Joe Kelly, who was 3-0 with a 1.61 ERA in his last five games (four starts) against the Cubs, was tagged for five runs over 4 2/3 innings while Wood was charged with five runs (two earned) in five frames. … The Cardinals, who scored a total of five runs over their previous three contests, amassed their highest offensive output in seven games. … Rizzo singled in the third to extend his hitting streak to 10 games and reached base three times after getting hit a second pitch from Pat Neshek in the eighth.