Schafer underwent an X-ray, which was negative. He received treatment postgame and will have further tests on Monday to determine the extent of the injury.
Schafer was removed in the top of the third inning. He and right fielder Justin Maxwell converged on a line drive to right-center field and had to avoid a collision. Neither made the catch. The ball squeaked between Schafer and Maxwell and bounced to the outfield wall.
After limping over to the ball, Schafer threw it into the infield, but not in time to prevent the Rangers' David Murphy from scoring on a three-run inside-the-park home run. The Rangers led, 4-0, at that point.
Schafer walked off the field under his own power but couldn't put pressure on his right foot walking down the dugout stairs. Maxwell moved over to center field to take Schafer's spot and Brian Bogusevic entered in right field.
Maxwell said he and Schafer never touched one another while trying to make the catch.
"I had a pretty good beat on the ball. I just missed it," Maxwell said. "We both have good instincts out there. It was almost pretty disastrous for us, not going to lie. Hope he's OK."
Schafer was receiving treatment on the ankle and was unable to comment.
Schafer missed more than two weeks in Spring Training with a sprained wrist and has taken a beating in the regular season. He's had lower hip/back tightness and suffered dizziness when he took a knee to the head in the second week of the season.
He struck out in his only at-bat Saturday and is hitting .254 with two home runs and 11 RBIs as the Astros' regular leadoff hitter.