"It's in my heel, but like, right up above my heel, under my Achilles, I guess," Rasmus said. "I don't think it's [anything] that serious."
The club considers Rasmus' condition a day-to-day matter. However, manager Tony La Russa said on Tuesday that he expects to sit the rookie outfielder in Wednesday's series finale against the Brewers. The Cardinals are off on Thursday before beginning a homestand Friday against Atlanta.
"We'll stay away from him," La Russa said. "It's something he's battling. He had that heel thing. The Achilles thing is probably directly related to it. Yesterday, I would not have used him for defense [but] I don't know that he's not available today."
It's just the latest in a run of maladies for Rasmus in his rookie season. In addition to the lingering heel issue, he also dealt with a hiatal hernia earlier in the year.
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.