Stewart (undisclosed) is expected to be placed on the injured list Wednesday, Betsy Helfand of the St. Paul Pioneer Press reports.
The move isn't official yet and his injury isn't clear, but it's not surprising given his struggles since his return from shoulder tendinitis on July 24 -- he's given up seven runs and seven hits in 2.1 innings over three outings with a 3:2 K:BB in that span.