Mason has 10 days to prepare for the 49ers' Week 7 matchup against the undefeated Kansas City Chiefs. If Mason isn't able to suit up, the 49ers will rely on rookie running back Isaac Guerendo and fourth-year running back Patrick Taylor Jr.

Mason injured his shoulder in the second quarter of the 49ers’ Week 6 win over the Seattle Seahawks. He returned for the second half, but exited after aggravating the shoulder on the first play of the third quarter. He spent the remainder of the game on the sideline and head coach Kyle Shanahan didn’t have much information after the game.

Mason was off to a good start on Thursday night when he was tackled and immediately grabbed at his shoulder area in a game against the Seattle Seahawks. He stayed down for a while while athletic trainers tended to him. Mason went back to the locker room and the 49ers said he was questionable to return with a shoulder injury.