Astros to evaluate Oswalt

CHICAGO -- Houston ace Roy Oswalt will rejoin the Astros in St. Louis on Friday and be evaluated to see if he can make his scheduled start Sunday.

Oswalt left Tuesday's game against the Chicago Cubs in the second inning after experiencing discomfort in his back. He returned to Houston and was given an injection Wednesday to treat an irritated disk. He will be evaluated over the next couple days to determine if he can pitch Sunday.

Houston will also monitor first baseman Lance Berkman on Friday. Berkman was placed on the disabled list July 23 with a strained left calf.

"I've got to see them and see what they can do," Astros manager Cecil Cooper said of Berkman and Oswalt.

Relief pitcher Wesley Wright was diagnosed with dehydration Tuesday after being sent to the hospital when he experienced abdominal pain. Wright pitched 2 1/3 innings in relief of Oswalt on Tuesday. After being advised to stay in his hotel room Wednesday, Wright rejoined the team on Thursday at Wrigley Field.