Graveman (neck) was placed on the 10-day injured list Tuesday.
Graveman battled neck stiffness during Sunday's start, but he'll be forced to miss several turns through the rotation after being diagnosed with neck spasms Tuesday. The Mariners were using a six-man rotation prior to the right-hander's injury, so the team could simply shift to a five-man group while he's on the shelf. Right-hander Joey Gerber and lefty Taylor Guilbeau were each added to the active roster in corresponding moves. It's unclear when Graveman could be ready to return to game action.