The 49ers wouldn't have beaten the Seahawks this past Thursday night without rookie running back Isaac Guerendo. The 49ers had a 20-point lead, but starting running back Jordan Mason left the game with a sprained AC joint in his shoulder.

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 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.