The 49ers already are without starting running back Christian McCaffrey, likely for a few more weeks. Now, at least temporarily, they are without his backup, Jordan Mason.
Mason was injured on a 14-yard run when he landed on his left shoulder with the weight of safety Julian Love landing on him. He remained on the ground after the play.
Mason headed to the X-ray room and his return his questionable.
He entered the game with a league-leading 105 carries for 536 yards and three touchdowns and has rushed for 65 yards on eight carries tonight. Mason also has a 9-yard reception.
Rookie Isaac Guerendo has replaced Mason.
The 49ers lead the Seahawks 16-0.
UPDATE 9:50 P.M. ET: Mason has returned for the second half.
