Kelly (4-3) struck out six and limited the Cubs to four hits and three walks while winning his fourth straight decision. He has not lost in seven starts since July 6 to help the Cardinals pull within two games of first-place Pittsburgh in the National League Central.

Cubs starter Travis Wood (7-10) failed to record a quality start for only the fifth time in 25 outings this year, allowing four runs on as many hits over 5 1/3 innings.

The Cardinals took a 1-0 lead in the fourth on Carlos Beltran's RBI double and made it 2-0 when a mental lapse by Chicago shortstop Starlin Castro turned into a strange sacrifice fly for Matt Carpenter. After making a catch in shallow left in the fifth, Castro paid no attention to Jon Jay, who raced home from third.

Molina's two-run blast in the sixth made it 4-0 and chased Wood. Nate Schierholtz had two of the Cubs' five hits as Chicago was shut out for the fifth time in its last seven home games.

GAME NOTEBOOK: Castro was benched at the end of the half-inning following his lapse, with Cody Ransom entering the game at third base and Donnie Murphy sliding over to shortstop. … Wood dropped to 2-6 against NL Central opponents. … The Cardinals took an 8-7 lead in the season series.