Cardinals starter Jake Westbrook (12-9) allowed one earned run and five hits, but pitched just 3 1/3 innings as manager Tony La Russa deployed seven pitchers on the night.
The Cards threatened in the eighth, down 3-0. Consecutive singles by John Jay, Albert Pujols, Lance Berkman and David Freese got the Cardinals within 3-2. But another former Astro, Brad Lidge retired Allen Craig on a ground ball to second base on his first pitch to escape the jam.
The tables turned quickly, as a Daniel Descalso error, a pair of singles and a hit-by-pitch opened the eighth. Dotel entered, relieving Marc Rzepczynski, and after an infield single to short drove in the second run of the frame, Ibanez' grand slam to right ended any doubt.
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