Raheem Mostert's Knee Injury Isn't a Torn ACL, per 49ers HC Kyle Shanahan

San Francisco 49ers running back Raheem Mostert left Sunday's game against the Detroit Lions with a knee injury.

The team confirmed in the third quarter that the 5'10" ball-carrier won't return. He carried the ball two times for 20 yards prior to exiting.

After the game, 49ers head coach Kyle Shanahan told reporters the medical staff "assured him" the injury is not to Mostert's ACL.

Mostert missed eight games last year, but his production in half a season raised expectations for what he could deliver in 2021. He finished with 677 yards from scrimmage and three touchdowns.

His absence reveals how much depth the Niners have at running back and how interchangeable those players can be in Kyle Shanahan's offense.

Tevin Coleman and Matt Breida combined to run for 1,167 yards in 2019, Shanahan's third as the team's head coach. With Breida gone and Coleman limited to eight games (one start) in 2020, Jeff Wilson Jr. finished as the team's leading rusher (600 yards) and averaged a healthy 4.8 yards per carry.

Another feature back is now emerging for the team.

Elijah Mitchell, a sixth-round rookie out of Louisiana-Lafayette, carried the ball 19 times for 104 yards and one touchdown. Another of San Francisco's draft picks is still waiting to make his full debut, as third-rounder Trey Sermon was a healthy scratch for Week 1.

For other teams, losing a running back with Mostert's ability could be a tough blow because he has been a steady presence in the 49ers backfield.

In the case of San Francisco, there probably won't be too many concerns about how the offense performs following his injury.