Jones (calf) was limited at Tuesday's walk-through, Rob Demovsky of ESPN.com reports.
Jones and Tyler Ervin are the only available running backs on the active roster, with Dexter Williams waiting in the wings on the practice squad, after Jamaal Williams (not injury related) landed on the reserve/COVID-19 list due to being a high-risk close contact of AJ Dillon (illness). Jones seems to have a chance to play Thursday at San Francisco after practicing for the first time since Week 6 prep, but much may depend on how he fares in Wednesday's session. If he's able to prove his health, he likely will be the lead back, with Ervin and potentially practice-squadder Williams taking on complementary roles.