Astros interim manager Tony DeFrancesco said Monday that Schafer aggravated the injury diving in the outfield for a Jay Bruce triple on Sunday in Cincinnati.
"We're going to have to keep an eye on him and see where he's at," DeFrancesco said.
Altuve, the All-Star second baseman, strained an abdominal muscle Friday and hasn't played since. He said Monday he was close to returning and should be able to hit on the field Tuesday. "It's real close to getting back to play," he said.
Moore is taking swings in the cage and fielding ground balls hit right at him with hopes of returning in the next couple of days. He left Wednesday's game at Pittsburgh with a left groin strain. Laird missed the Cincinnati series with flu-like symptoms, but said Monday he felt better.