San Francisco head coach Kyle Shanahan said Monday that Mitchell (knee) is expected to be sidelined for 6-to-8 weeks, Matt Maiocco of NBC Sports Bay Area reports.
Per Nick Wagoner of ESPN.com, the 49ers plan to place Mitchell -- who is believed to be dealing with an MCL sprain of his left knee -- on injured reserve, which would ensure that he misses at least four games. However, based on the estimated timetable put forth by Shanahan, the running back doesn't seem likely to return before the postseason. In Mitchell's looming absence, Tyrion Davis-Price and Jordan Mason are now in line to log complementary snaps for the 49ers behind top back Christian McCaffrey. Tevin Coleman could be promoted from the team's practice squad to provide additional depth to the position group.