The Cubs placed Boyd on the 15-day injured list Monday with a left bicep strain, Meghan Montemurro of the Chicago Tribune reports.
Boyd didn't suffer the injury at any one time but was having trouble bouncing back in between starts. The left-hander expects his absence to be a brief one. It's another blow to a Cubs rotation that also recently lose Cade Horton (forearm) to an arm injury. Javier Assad will start Tuesday versus the Rays in Boyd's place.