Messick will be the Guardians' starter for Sunday's regular-season finale against the Royals, Tim Stebbins of MLB.com reports.
The Guardians secured the AL Central division Saturday -- and the No. 2 seed in the AL playoffs -- following their win over Kansas City and the White Sox's loss to the Rockies. Still, the Guardians will have Messick toe the rubber Sunday, though it will likely be an abbreviated outing for the 25-year-old southpaw.