Twins president of baseball operations Derek Falvey said Monday that Thielbar (hamstring) will begin the season on the injured list, Bobby Nightengale of the Minneapolis Star Tribune reports.
Thielbar had a setback with his left hamstring during Saturday's live batting practice session. There's no timetable at this juncture for the left-handed reliever's return. It's a blow to a bullpen that will also be without Jhoan Duran (oblique) at the start of the season.