Expected to miss eight weeks

Mostert (knee) is expected to miss about eight weeks and will go on IR, Nick Wagoner of ESPN.com reports.

Mostert exited Sunday's win over the Lions with a knee injury, which turns out to be chipped cartilage. Rookie sixth-round pick Elijah Mitchell took over for Mostert against Detroit and rushed for over 100 yards, so he'll likely lead San Francisco's backfield in Mostert's absence. JaMycal Hasty and rookie third-round pick Trey Sermon should also see additional opportunities while Mostert recovers.

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Elijah Mitchell

RB | SF

Not seen Thursday

Mitchell (shoulder) wasn't present at the start of Thursday's practice, Matt Barrows of The Athletic reports.

Jacques Patrick

RB | SF

Signs on with Niners

Patrick will be signed by the 49ers on Tuesday off the Bengals' practice squad, Tom Pelissero of NFL Network reports.