Mason took nine carries for 59 yards and recorded one catch for 13 yards in Friday's 23-12 preseason loss to the Chargers, but he lost a fumble at the goal line on the opening drive.
With Christian McCaffrey and Elijah Mitchell held out, Mason dominated first-team snaps on a night that saw Brock Purdy, Deebo Samuel, Brandon Aiyuk and George Kittle all playing. They faced the Chargers' second-team defense and would've scored 14 points in two drives if not for Mason losing a fumble at the goal line. Tyrion Davis-Price then dominated backfield work with the second-stringers en route to 12 touches for 76 yards, perhaps giving the Niners a tougher decision between him and Mason for the No. 3 RB job. Keeping both isn't out of the question.