Mostert (knee) was placed on injured reserve Tuesday.
San Francisco officially removed Mostert from its 53-man roster a few hours after the running back announced he would undergo season-ending surgery to address the cartilage damage in his knee he sustained Sunday. Mostert expects to be back to 100 percent health for the start of the 2022 campaign, but he could be suiting up for a different team, as he'll become a free agent during the upcoming spring. Meanwhile, the 49ers are expected to give Elijah Mitchell the first crack at the No. 1 role out of the backfield, with Trey Sermon and JaMycal Hasty on hand in complementary roles. Additionally, San Francisco signed veteran Kerryon Johnson to its practice squad Tuesday, and he could eventually factor into the backfield equation.