Left-handed pitcher Pedro Hernandez was optioned to Triple-A Rochester while starting pitcher Kyle Gibson was recalled from there. Gibson is scheduled to make his major-league debut on Saturday against the Royals at Target Field.
Gibson, 25, was taken in the first round in the 2009 draft out of the University of Missouri.
The 6-foot-6 right-hander is 7-5 with a 3.01 ERA, 1.14 WHIP and 79 strikeouts in 92 2/3 innings in Triple-A this season. He entered the year ranked as the 68th-best prospect in baseball by Baseball America.