That was good news for manager Cecil Cooper, who hopes to get at least 13 more starts from Oswalt.
"Roy came up and said he was fine," Astros manager Cecil Cooper said. "He threw everything. He let it all go."
Oswalt was 7-8 with a 4.56 ERA in 19 starts before being placed on the 15-day disabled list July 19, retroactive to July 12. An MRI on July 19 confirmed that he had a strained left hip abductor and a herniated disk in his back.
His last start was July 11 at Washington, when he went one inning.
"I'm ready to get back out there," he said. "Hopefully, go out there Monday and get in a groove early and (be) able to go deep in the ball game."
Cooper said that Oswalt will have a 90-pitch limit for his start, if there are no problems.
The Astros would activate Oswalt after Sunday's game or before the game Monday.