ARLINGTON, Texas -- Houston Astros left-hander Framber Valdez will miss his scheduled start Sunday against AL West-leading Texas because of right ankle soreness.

Manager Dusty Baker said Saturday that Valdez (7-6, 2.49 ERA) sprained his ankle on June 20 in a game against the New York Mets, even though he made his next scheduled start in St. Louis.

"In New York, he sprained his ankle pretty badly. We didn't know if he was going to start his next start," Baker said. "Then, against St. Louis, it affected his delivery. So we decided to skip him this time and hopefully he'll pitch again before the (All-Star) break."

Baker didn't say who would pitch in place of Valdez in the third game of the Astros' four-game series against the Rangers.

Valdez allowed eight hits and three walks over six innings in a 4-2 loss to the Cardinals last Tuesday. The lefty had struck out nine over eight innings in a 4-2 win over the Mets a week earlier.

"Then it got worse. He was trying to get it loose up and down the stairs and it, as you saw, it affected his delivery against the Cardinals," Baker said. "He was getting balls up, balls that were supposed to be sinking. It's just something we have to deal with."