KANSAS CITY, Mo. (AP) — The Royals placed left-hander Bruce Chen on the disabled list Friday with a bulging disk in his back and recalled right-hander Aaron Brooks from Triple-A Omaha.

Chen was supposed to start Saturday against Detroit, but he struggled with the pain in a side session on Thursday, even after receiving an epidural that was supposed to alleviate it.

Afterward, Royals manager Ned Yost acknowledged that a DL stint was likely.

Left-hander Danny Duffy will slide from the bullpen into Chen’s spot in the rotation.

Brooks, who was 0-1 with a 4.80 ERA at Omaha, provides some bullpen depth. He spent five days with the Royals in early April but did not appear in a game.