Mitchell (knee) has been ruled out for Sunday night's game against Dallas, Matt Barrows of The Sacramento Bee reports.
Christian McCaffrey figures to dominate backfield snaps in any case, given that Sunday's game could end up making the difference between a bye week and a wild-card game in January. Mitchell had 19 touches over the first three weeks of the season before the knee injury sidelined him, but even that limited workload largely was earned in the late stages of blowouts. Most of the fantasy appeal at this point is based on what Mitchell might do in the event of a McCaffrey injury, rather than any hope of the San Francisco backfield supporting two fantasy starters at the same time (something that looked possible at one point last winter).