The San Francisco 49ers and running back Jordan Mason might have avoided disaster.

Mason injured his shoulder in the second quarter of the 49ers' Week 6 win over the Seattle Seahawks. He returned in the second half but left after suffering a shoulder injury on the first play of the third quarter. He spent the rest of the game on the sidelines and head coach Kyle Shanahan didn't have much information after the game.

ESPN's Adam Schefter reported Friday morning that the injury was believed to be a sprained cruciate joint, which was not considered serious. Mason will undergo further testing on Friday.

Head coach Kyle Shanahan will speak with reporters Friday afternoon and may provide more information on the 49ers' breakout star.

If the 49ers can avoid something big happening with Mason, it would be a significant win for them considering the impact he has had on their offense. Their running game in Seattle was difficult without him, except for rookie RB Isaac Guerendo's game-winning 76-yard run. Guerendo would be Mason's replacement if he is unable to play in Week 7 against the Chiefs.

Mason finished Thursday's game with 73 yards on nine carries. He also managed a 38-yard run in the game, which marked his longest run of the season.

After Week 6, he had an NFL-best 609 yards rushing on 114 carries.