Royals right-hander Kris Medlen experienced a setback in his hopeful return to the Major League rotation after suffering a right shoulder strain during a rehab assignment with Triple-A Omaha on Tuesday.
Medlen, who has been on the disabled list since May 12 with right rotator cuff inflammation, left after throwing a breaking ball on his 49th pitch. He will be re-evaluated on Wednesday in Kansas City.
In six Major League starts this year, Medlen was 1-3 with a 7.77 ERA. He is 0-2 with a 5.50 ERA in five starts in the Minors.