The Astros have placed pitcher Roy Oswalt on the disabled list with a left hip abductor strain that was suffered in late June, according to MLB.com. Oswalt was previously scheduled to throw a bullpen session on Saturday afternoon in hopes that he could re-enter Houston's rotation on Tuesday. He was placed on the 15-day disabled list retroactive to his one-inning, 17-pitch start on July 11 against the Nationals.