Mostert suffered a calf injury during Saturday's divisional-round game against the Vikings, Keiana Martin of the 49ers' official site reports.
Considering he picked up the issue in the fourth quarter, Mostert is unlikely to make his presence felt again Saturday. Prior to his departure, he had 12 carries for 58 yards and recovered a muffed punt. Meanwhile, Tevin Coleman returned to a lead-back role, with more than 100 yards on the ground.