The Giants placed Roupp on the 15-day injured list Friday with left knee inflammation.
The club is calling it inflammation for now, but Roupp underwent an MRI on Thursday and a more specific diagnosis could come Friday, per Alex Pavlovic of NBC Sports Bay Area. Roupp was injured during Wednesday's start versus the Padres after being struck by a comebacker and then twisting awkwardly when he fell to the ground. Carson Whisenhunt is taking Roupp's spot on the roster and in the rotation.