Quarterback Bo Levi Mitchell was at Calgary Stampeders practice Tuesday but only as a spectator.

Mitchell left the Stampeders' 36-32 win over the BC Lions Saturday with what he believed was a pectoral injury. The 29-year-old was scheduled for an MRI today after practice.

If Mitchell misses any time, backup quarterback Nick Arbuckle, who orchestrated the Stampeders' late-game comeback for the win Saturday, would start in his place.

In other Stampeders injury news, head coach Dave Dickenson said starting defensive end Ivan McLennan will require surgery for a knee injury, per Postmedia's Danny Austin.

"McLennan tore multiple ligaments in his knee, which was also dislocated, and will require surgery. And he also broke his hand on the same play," Austin reported.

Running back Don Jackson and receiver Juwan Brescacin are both in concussion protocol, per Austin, though Brescacin could handle a little more in meetings than Jackson.