The 49ers are promoting practice squad running back Raheem Mostert to the 53-man roster for the final game of the regular season, according to his agent, Brett Tessler.
The club is expected to announce the corresponding move by 1 p.m. Two offensive linemen, Marcus Martin and Andrew Tiller, have already been ruled out for Sunday's game against the Seattle Seahawks due to ankle injuries. Mostert is expected to take the role of Mike Davis, who appeared to foreshadow a move.
"Guess I gotta work even harder," Davis wrote Friday on his Twitter account.
Shaun Draughn and DuJuan Harris are the two other healthy running backs on the 49ers' roster. Carlos Hyde was placed on injured reserve this week with a knee injury.
Mostert, who spent the past four weeks on the practice squad, entered the NFL last season with the Philadelphia Eagles as an undrafted free agent. He has also spent time with Miami, Baltimore Cleveland, the New York Jets and Chicago.
He appeared in 11 games last season with three different teams. He played two games earlier this season with the Bears. He has never carried the ball in an NFL game, but he has averaged 27.9 yards on 19 kickoff returns.
Mostert (5 foot 10, 197 pounds) rushed for 529 yards and three touchdowns on 93 rushing attempts as a senior at Purdue in 2014.