Calgary Stampeders quarterback Bo Levi Mitchell has been placed on the six-game injured list.

The CFL's most outstanding player and Grey Cup MVP in 2018 injured his throwing arm late in last Saturday's game against the B.C. Lions. He wasn't hit, but appeared to strain his arm throwing the football.

The Stampeders have not revealed Mitchell's exact injury, though the quarterback has indicated he felt pain in his right pectoral muscle. Calgary can pull Mitchell of the injured list at any time, but while he is on it, his salary does not count against the cap.

With Mitchell out, the Stampeders have Nick Arbuckle at the top of the depth chart for Saturday's road game against the Saskatchewan Roughriders. The 25-year-old Arbuckle, in his second season on the Stamps' active roster, will be making his first career CFL start.

Mitchell is expected to be the fourth CFL opening-day starting quarterback to miss a game because of injury in the 2019 season, which is in its fourth week.

The others are Zach Collaros of the Saskatchewan Roughriders, Antonio Pipkin of the Montreal Alouettes and James Franklin of the Toronto Argonauts.