Mauer had the examination on Tuesday and was out of the lineup against the Detroit Tigers for the fourth straight game. Manager Ron Gardenhire says the test revealed a deep soft tissue bruise. The reigning AL MVP remains day to day.
Wilson Ramos started at catcher again in place of Mauer. Ramos had seven hits in nine at-bats in his first two major league games.
The Twins activated right-hander Nick Blackburn from the family medical leave emergency list to start the game against the Tigers. Blackburn has been tending to a family matter since April 30.
The Twins optioned right-hander Jeff Manship to Triple-A Rochester to make room.