Oswalt left Tuesday's game in Chicago with a strained left lower back, but he's made enough progress to feel that he won't have to go on the disabled list. His turn in the rotation Sunday was taken by rookie right-hander Bud Norris.
Houston general manager Ed Wade said on Saturday the club was considering calling up Felipe Paulino to start Tuesday against the Giants in the rotation spot that became vacant when Russ Ortiz was released. Wade said Oswalt was a candidate to start Tuesday if he felt better, but Oswalt's goal is Saturday.
"That's my target," he said. "I don't know what their target is."
Oswalt said he threw Sunday at about 75 to 80 percent and felt pretty good. The big test will come Monday, when he's set to throw in the bullpen at Minute Maid Park.
"If I feel great Wednesday, I might try to get in the bullpen and throw an inning in the 'pen and make sure I'll be ready for game action Saturday," Oswalt said.
Paulino was scheduled to start Saturday at Triple-A Round Rock, but he was scratched in anticipation of perhaps throwing in Houston on Tuesday. Paulino, who is 2-5 with a 7.04 ERA for the Astros this year, is 1-0 with a 2.25 ERA in five starts at Round Rock.
Yorman Bazardo (9-5, 2.98 ERA) has been Round Rock's top starter this year, but he's out of options. If the Astros brought him up to make a spot start, he would have to clear waivers to make it back to Round Rock.
"From a logistical standpoint, Paulino was the obvious choice at this stage," Wade said. "Bazardo was a consideration, but from a roster standpoint, he has no options remaining, and if we were to bring Yorman up at that point in time, we're pretty much locked into keeping him. That creates a domino effect when Oswalt comes back and [LaTroy] Hawkins comes off the DL. So we had to sort of look at it in the short-term and long-term.
"Short-term, because we may need to cover two starts, and long-term if you cover with a guy like Bazardo, it could impact the structure of the pitching staff and put him in position we have to put him on waivers to get him back down. Every little roster move has ramifications, and we need to try to think these things through."
Meanwhile, left-hander Wandy Rodriguez, who left Saturday's game after four innings with a right hamstring strain, said he felt better Sunday and would be able to make his next start.
"He's better, but we still have to wait until the throws a bullpen," manager Cecil Cooper said.
Infielder Darin Erstad is eligible to come off the disabled list Monday, but his strained left hamstring is still not ready. Hawkins, placed on the disabled list last week with shingles, joined the team Sunday after spending two days at home in Gary, Ind.
"I'm walking better and feeling better," Hawkins said. "The spasms are not that close together anymore. The way I'm feeling and progressively getting better, I don't see reason why I shouldn't be [able to come to come off the disabled list when scheduled]."
Brian McTaggart is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.