The Twins will place Thielbar (groin) on the 10-day injured list prior to Thursday's game against the Royals, Dan Hayes of The Athletic reports.
Minnesota will call up Shaun Anderson to fill the opening on the 26-man active roster and in the bullpen after Thielbar suffered a strained left groin during his relief appearance Wednesday in Baltimore. Thielbar has been a key part of the bridge to closers Hansel Robles and Taylor Rogers this season, accruing a 4.29 ERA, 1.48 WHIP, 31 strikeouts and five holds over 20 appearances.