Pinch-hitter Pedro Feliz hit a two-run double in Houston's four-run sixth inning and the Astros extended the Pittsburgh Pirates' skid to seven games with an 8-2 victory Sunday.
Hunter Pence and Chris Johnson had three hits apiece for Houston, which trailed 2-1 after five innings. Jeff Keppinger had two RBIs.
J.A. Happ (3-1) allowed two runs and three hits in six innings to improve to 2-1 in four starts since he was acquired from Philadelphia in the Roy Oswalt trade.
Pence started the winning rally with a leadoff double against Jeff Karstens (2-9). Pence moved to third on Carlos Lee's fly ball and scored on Keppinger's tying sacrifice fly.
After Brett Wallace was hit by a pitch, Johnson reached on an infield hit and Jason Castro hit a tiebreaking RBI single before Feliz's double to center off Sean Gallagher made it 5-2.
Karstens was charged with five runs and seven hits in 5 2-3 innings as Pittsburgh lost its 10th straight road game. Karstens has dropped his last seven decisions.
Plate umpire Alan Porter had to leave in the sixth inning after he was struck on the head on Lee's swing. Porter walked off the field and required five stitches to close a laceration.
Second base umpire Hunter Wendelstedt moved behind the plate to finish the game.
Pittsburgh pushed across two runs in the fourth to take a 2-1 lead. Neil Walker's sacrifice put runners on second and third for Lastings Milledge, who singled to center for the Pirates' first run. Chris Snyder followed with a sacrifice fly.
Happ's wildness almost cost him in the sixth. He walked Pedro Alvarez and Walker with one out. Milledge then hit a roller to second baseman Keppinger, forcing Walker at second.
Shortstop Angel Sanchez's throw to first was high and Milledge was safe, but first baseman Wallace cut down Alvarez trying to score, ending the inning.
NOTES: The Astros are 34-31 since their 17-34 start.