The 49ers didn't activate Sermon (ankle) from injured reserve before Thursday's game at Tennessee, Matt Maiocco of NBC Sports Bay Area reports.
Sermon was designated to return from IR on Wednesday, so it's no surprise he was unable to prove he wasn't past his sprained right ankle. With Elijah Mitchell (knee) absent for a third consecutive game, Jeff Wilson will act as the 49ers' primary running back Thursday, while the likes of JaMycal Hasty, Brian Hill, wide receiver Deebo Samuel and fullback Kyle Juszczyk mix into the backfield as well.