San Francisco RB Michael Robinson fumbled on the 49ers first play of the game in Sunday's preseason game against the Colts. Robinson and rookie Anthony Dixon are vying for the backup running back spot behind Frank Gore, after the sudden retirement of second-year back Glen Coffee. Robinson carried the ball five times for 13 yards and a 3-yard score. Robinson -- a converted quarterback -- has become a versatile back, but is known for his sloppy play. Granted he did score in Sunday's game, but starting off with a fumble is not a good way to impress the coaches. Source: CBS Sports