Manager Mike Matheny said Friday that he expects Castillo to start Sunday's game against the Tigers, Joel Goldberg of Bally Sports Kansas City reports.
Castillo was sent down by the Royals on Aug. 20, but he should rejoin the major-league club for Sunday's series finale in Detroit. While the Royals have some off days over the next few weeks that could allow them to use a five-man rotation, Castillo should have a chance to earn additional starts after he posted a 2.81 ERA and 0.94 WHIP in 25.2 innings over 10 appearances (three starts) in the majors earlier this year.