"Maybe a day or two," Ankiel said on Monday when he was asked about his status.
Ankiel explained that he didn't suffer the injury on an overswing. Instead, he got off-balance on a swing, with his hands too low, and tweaked his shoulder as he was trying to get his balance right again.
It's growing clearer that the outfielder is unlikely to head to the disabled list.
"He's improving," manager Tony La Russa said. "He's on the active list. We'll see how he feels and how much we can use him."
Skip Schumaker started in Ankiel's place in center field for St. Louis on Monday, flanked by Ryan Ludwick in right and Brian Barton in left.
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.