The Nationals have placed pitcher Doug Fister on the 15-day disabled list with a strained muscle on the right side of his upper back.
The move is retroactive to March 23. The Nationals made the announcement Saturday in finalizing their opening day roster after their scheduled exhibition game against the Detroit Tigers was canceled because of rain.
Fister will be shut down for five days before resuming his rehabilitation. The right-hander, obtained in an offseason trade with Detroit, is expected to miss anywhere from three weeks to 30 days, manager Matt Williams said.
Taylor Jordan takes over the No. 5 spot in Washington's rotation.