Mitchell (knee) underwent an MRI on Monday and is expected to miss time, Ian Rapoport of NFL Network reports.
The 49ers will have a clearer picture of Mitchell's recovery timetable once the MRI results reveal the full extent of his right knee injury. The second-year running back was ruled out of Sunday's loss to the Bears after San Francisco's fourth possession, and he was spotted after the contest wearing a brace. An extended absence on Mitchell's behalf likely would propel Jeff Wilson into the No. 1 running back spot, and likewise mean increased work for rookies Jordan Mason (zero touches Week 1) and Tyrion Davis-Price (inactive Week 1). Deebo Samuel also could factor in for more backfield action.