Mostert was placed on injured reserve Tuesday to a left high-ankle sprain, spelling an end to his 2020 season, Tom Pelissero of NFL Network reports.
Mostert's season was plagued by injuries, as ankle and knee injuries will end up costing him eight games this year. The 28-year-old rushed 104 times for 521 yards and two touchdowns, and he caught 16 of 19 targets for 156 yards and a score. The 49ers will close out the 2020 campaign with a committee of Jeff Wilson (ankle), Tevin Coleman and Jerick McKinnon at running back. Mostert is under contract for the 2021 season at a $3.3 million cap hit.