Guerendo (foot) won't participate in Tuesday's walk-through practice, Nick Wagoner of ESPN.com reports.
Guerendo will go down as a non-participant on the 49ers' second injury report of the week. With the team facing a quick turnaround ahead of a Thursday night matchup with the Rams, the rookie running back looks like he may be facing an uphill battle to gain clearance after exiting a Week 14 win over the Bears with a sprained foot. Guerendo looked good in his first NFL start, gaining 78 yards and two touchdowns on 15 carries to go with two catches for 50 yards. If the Louisville product ends up missing Thursday's game, Patrick Taylor, Ke'Shawn Vaughn and Israel Abanikanda would represent the 49ers' available options at running back.