Setting up Pujols' heroics, pinch hitter John Rodriguez, who has had success against Houston closer Brad Lidge, singled to open the ninth. After Rodriguez was bunted to second, Scott Spiezio was hit in the foot by a pitch with two outs.
Pujols fell behind 1-2 in the count, but Lidge got a pitch a bit too far inside and up, and Pujols muscled it into left field. Houston's Jason Lane could not play the ball quickly enough to prevent Spiezio from scoring all the way from first base.
Braden Looper turned in two scoreless innings of relief and was rewarded with his ninth victory in 10 decisions.
REPLAY: The Cardinals beat Houston closer Brad Lidge a little more softly than when Albert Pujols rocketed a game-winning home run in Game 5 of last year's National League Championship Series. This time, Pujols, after fouling strike two off his foot, lofted a double into the left field corner to chase home two runners and provide the Cardinals a 6-5 victory Tuesday.
In beating the Astros for the fifth consecutive time, the Cardinals rallied from three deficits (they also blew two leads).
--3B Scott Rolen, having enough trouble in going hitless in his last 13 at-bats, was run by plate umpire Tim Tschida for protesting a third-strike call in the fifth inning.
--RHP Jeff Weaver surrendered two leads, the second coming when he gave up a two-run homer to Houston 2B Chris Burke in the sixth inning. Weaver allowed left-handed batters to get five hits in 13 at-bats Tuesday, matching the .385 mark against left-handers he had brought into the game. Weaver still is winless at home, 0-3.
--1B Albert Pujols' ninth-inning double gave him his 23rd game-winning RBI of the season.
--The Cardinals scored all six of their runs with two outs, and 12 of their 13 in the series have come with two outs.
--RHP Braden Looper has nine relief wins, the most by a Cardinals reliever since RHP Mark Petkovsek won 11 in 1996. Looper's win total is tops for a National League reliever.
--LHP Mark Mulder had surgery Tuesday to fix a partial tear in his left rotator cuff. He hopes to be ready in time for spring training.
BY THE NUMBERS: 84.7 -- Career percentage of saves converted by RHP Jason Isringhausen, even though he has blown 10 of 43 this season.
QUOTE TO NOTE: "It might make some people happy." -- RHP Jason Isringhausen, on the possibility he won't be able to pitch anymore this season.