Two errors opened the door for a four-run seventh inning, while Lance Berkman and Hunter Pence added homers in the eighth as the Houston Astros rallied to beat the St. Louis Cardinals 6-3 Tuesday night at Busch Stadium.

The Cardinals can't seem to put things together for Brad Penny, who lowered his ERA to 1.70 by going seven innings without allowing an earned run, giving up seven hits and striking out three. Penny (3-3) has been plagued by a lack of run support all season and this time St. Louis' sloppy defense also hurt him. The Cardinals made three errors, including a pair that led to four unearned runs in the seventh.

Astros starter Brett Myers (2-2) left the mound after the sixth looking as though he might be on his way to another tough-luck loss, but Houston's rally changed that. Myers allowed two runs on eight hits, walking two and striking out three, but trailed 2-0 through six.

The Astros got him off the hook in the seventh, aided by errors charged to shortstop Brendan Ryan and catcher Yadier Molina.

Tommy Manzella, Michael Bourn and pinch-hitters Cory Sullivan and Humberto Quintero drove in runs in the inning.

Berkmana and Pence hit a pair of solo shots in the eighth inning off Jason Motte.

Matt Lindstrom pitched a scoreless ninth for his seventh save in as many chances.

Ryan Ludwick had three hits and an RBI for St. Louis. Matt Holliday and David Freese also drove in runs.