The 49ers are holding RB Trey Sermon out of Sunday night's preseason game against the Chargers. The rookie reportedly sustained a mild ankle injury during the practice week. According to Niners Nation, he returned to the field for the practice in which he came up "gimpy." That indicates it's not an issue we need to worry about. Raheem Mostert and Elijah Mitchell also won't play in the game, leaving more reps for Wayne Gallman and JaMycal Hasty.