The Twins recalled pitcher Michael Tonkin to the 25-man roster and optioned shortstop Jorge Polanco to a Double-A affiliate.
The Twins also designated pitcher Tim Stauffer for assignment.
Tonkin was recently with the Rochester Red Wings, the Triple-A affiliate of the Twins. With the Twins this year, he's posted a 5.63 ERA and 1.50 WHIP over eight innings of relief this season.