A's left-hander Rich Hill was placed on the 15-day disabled list with a left groin strain on Thursday, a day after reinjuring his groin during a bullpen session and being scratched from his next scheduled start.
The move was retroactive to May 30, meaning Hill will be eligble to return Wednesday.
Hill exited early from his most recent outing on May 29 against the Tigers, and he has not pitched in a game since then. The 36-year-old was scheduled to throw 35 pitches on the side at Miller Park on Wednesday, but he aggravated his groin in doing so.
Hill said he felt a "grabbing, pulling sensation" on his 33rd and 34th pitches, "essentially what I felt in the seventh inning [vs. Detroit]."
That led the A's to schedule Hill for an MRI on Thursday, and they subsequently placed him on the DL.
Hill is 8-3 with a 2.25 ERA in 11 starts this season, and he was named the American League Pitcher of the Month for May.