Schafer hurt his leg when he had to leap over a diving Justin Maxwell in the outfield while trying to track down a fly ball off the bat of David Murphy, who wound up with a three-run, inside-the-park homer.
Schafer was taken for X-rays, which were negative. He was walking without a limp Sunday morning and said he felt better. Maxwell started in center field in place of Schafer, who's hitting .216 in May.
"I'm still a little sore today," Schafer said. "I think I should be OK in a day or two. It will be all right."
Schafer said he will undergo more tests if the leg is still bothering him in a few days. He was going to try to get on the field and run on Monday.
"Right now, the doctor doesn't feel there's really any need to have an MRI unless he wakes up tomorrow and it's not very good, and then we're going to have an MRI," Astros manager Brad Mills said. "We'll see how he is [Monday] and go from there."