Willingham said he injured his shoulder while leaping near the left-field wall in an attempt to rob Eric Chavez of a homer in the seventh inning of Monday night's 6-3 loss. Before the results of Tuesday morning's exam were known, Willingham said he wasn't expecting any major damage.
"He's definitely sore," Twins manager Ron Gardenhire said of Willingham. "We'll call it day to day, but how many days, I'm not sure."
With Willingham out, Ben Revere shifted from his usual spot in right field to left, with Chris Parmelee getting the start in right.