Donnie Murphy and Darwin Barney each added two hits and an RBI for the Cubs, who evened the season series at 7-7. Arrieta (2-2) struck out seven and walked two in his second start with the Cubs, retiring 12 straight before issuing back-to-back walks with one out in the sixth.

Carlos Beltran had the only two hits for the Cardinals, who fell three games behind National League Central leader Pittsburgh. St. Louis remained a half-game ahead of Cincinnati for the top wild-card spot.

The Cubs grabbed a 3-0 lead in the first, taking advantage after Jake Westbrook (7-8) walked the first three batters. Schierholtz opened the scoring with a two-run single and Murphy added a run-scoring single later in the frame.

Westbrook allowed seven runs - six earned - on eight hits over 6 2/3 innings. He walked five and has permitted 15 bases on balls while losing his last four outings.

GAME NOTEBOOK: Arrieta has allowed only one run and four hits in 13 innings over his first two big-league starts since being acquired from Baltimore. … St. Louis LF Matt Holliday went 0-for-4, snapping his 12-game hitting streak. … Former Cubs 2B Ryne Sandberg was named interim manager of the Phillies on Friday. Philadelphia will be in Chicago for a three-game series starting Aug. 30.