The Twins placed left-hander Brian Duensing on the disabled list with a right intercostal strain on Friday, and they recalled left-hander Caleb Thielbar from Triple-A Rochester.
Duensing sustained the injury in the ninth inning of Thursday's game against the Royals.
Thielbar is 1-0 with a spotless ERA in three relief appearances spanning 2 1/3 innings this year with Rochester.
Over the last two seasons with the Twins, the 28-year-old made 103 relief appearances and posted a 5-3 record and a 2.59 ERA.
Duensing had a 7.36 ERA through six games (3 2/3 innings) this season.