Rollins reached first on a one-out fielder's choice against Barret Browning (0-2), moved to second on an out and stole third.
That brought up Pierre, who sent a grounder to shortstop Rafael Furcal. The speedy Pierre beat Furcal's long throw to first, allowing Rollins to come home with the decisive tally.
Jeremy Horst (1-0) tossed two scoreless innings to earn the win for the Phillies, who took the rubber match of a three-game series.
Erik Kratz forced extra innings with a two-out, three-run homer in the eighth and Ryan Howard went 2-for-3 with a solo shot and two RBI in the win.
Mike Carpenter went 4-for-6 with three RBI and John Jay added three hits and knocked in a pair of runs while scoring three times for St. Louis.