Shanahan added that C Ben Garland is also expected to join Mostert on injured reserve.
It’s worth mentioning that the NFL changed the rules regarding injured reserve for the 2020 season and players can return from the list after just three games.
Mostert missed some time earlier in the season with an MCL sprain.
Mostert, 28, wound up signing on with the Eagles as an undrafted free agent out of Purdue back in 2015. He had brief stints with the Dolphins, Ravens, Browns, Jets and Bears before signing on to the 49ers’ practice squad in 2016.
The 49ers brought Mostert back on a one-year exclusive rights contract in 2018 before tendering him a restricted offer in 2019. He later signed a three-year, $8.7 million extension with San Francisco.
However, the two parties agreed to a restructured contract this summer.
In 2020, Mostert has appeared in four games for the 49ers and rushed for 303 yards on 51 carries (5.9 YPC) to go along with 11 receptions for 150 yards and two touchdowns.