Mitchell was removed from Wednesday's game against the Cubs due to back tightness, Todd Rosiak of the Milwaukee Journal Sentinel reports.
Mitchell said after the game that his removal was precautionary, and he didn't seem too concerned about it becoming a serious issue. He'll have a chance to rest and recover during the Brewers' day off Thursday, which could help him return to the starting nine for Friday's series opener against the Dodgers. If Milwaukee elects to hold him out, Blake Perkins would be in line for a start in the outfield.