Coach Kyle Shanahan said Wednesday that Mostert (ankle) is considered "day-to-day," Chris Biderman of The Sacramento Bee reports.
The 49ers designated Mostert for a return from injured reserve Tuesday, and Shanahan's comments would seem to hint that the running back has a shot at returning to the lineup as early as Sunday's game against the Rams. Tevin Coleman (knee) also resumed practicing in a limited fashion Wednesday, so San Francisco's backfield appears set to receive some reinforcement in the near future.