Head coach Dave Dickenson was "99 percent sure" Mitchell would be the starter in Saturday's game against the Montreal Alouettes, however, the quarterback was bothered by his pectoral muscle throughout practice at the start of the week, Lalji added.
Mitchell has been on the six-game injured list since hurting his throwing arm in Week 3. The Stampeders have turned to Nick Arbuckle in Mitchell's absence and have gone 4-2 since he took over. With a record of 5-3, Calgary currently sits third in the West division.
Dickenson was cautious of a Week 12 return for his starting pivot, stating Mitchell would only return when he's "one thousand percent ready."