Gray (knee) was placed on the 10-day injured list Friday, retroactive to April 20.
The 30-year-old will miss some time with a low-grade MCL sprain in his left knee, though it isn't expected to be a lengthy absence. Gray suffered the injury during Tuesday's start against the Mariners, which was his first game back after going down with a finger injury Opening Day. Glenn Otto will step into his spot in the rotation and will pitch Friday in Oakland.