49ers' Raheem Mostert (knee) will not return to Week 1

San Francisco 49ers running back Raheem Mostert (knee) will not return to Week 1's game against the Detroit Lions.

What It Means:

Mostert has been downgraded to out and will not return to Sunday's game against the Lions.

Mostert will finish Week 1 with 2 carries for 20 yards.