With their bullpen exhausted after heavy usage this week, the Royals called up right-handed reliever Michael Mariot.
Mariot, 26, gave up a run in a two-inning appearance for Kansas City earlier this season.
He spent the majority of the season with Class AAA Omaha. Mariot finished the season with a 3.34 ERA in 62 innings for the Storm Chasers.
Before Saturday’s game against the Tigers, manager Ned Yost said Greg Holland, Wade Davis, Kelvin Herrera and Ryan Madson were all unavailable.