Jordan Mason leaves Week 6 game with sprained AC joint, is day-to-day [UPDATE]

Kyle Shanahan Friday update: The 49ers head coach met with the media on Friday following the team’s Week 6 win over the Seahawks. He said that Mason is day-to-day with his shoulder injury, per Jennifer Chan.

Day after update: The 49ers are taking a look at Jordan Mason’s shoulder, but ESPN’s Adam Schefter is reporting the running back appears to have suffered a sprained AC joint. Schefter tweeted that Mason will undergo additional tests on Friday to determine the severity, but the injury “is not considered serious.”

The San Francisco 49ers entered Week 6 struggling with a host of injuries. On Thursday against the Seattle Seahawks, they suffered another notable injury. Running back Jordan Mason injured his left shoulder in the second quarter after claiming the NFL lead in rushing. Mason landed on his shoulder and was taken to the locker room for x-rays at the 9:37 mark in the quarter.

Isaac Guerendo replaced Mason who was already starting in place of an injured Christian McCaffrey. The 49ers are hoping to get McCaffrey back by November, but in the meantime, they’ll be short-handed at the position. Guerendo had four carries for six yards after Mason left the game.

Mason entered Thursday with 536 rushing yards, but had 65 on eight carries to move him past Derrick Henry for the league lead. The team announced him as questionable to return.

2nd quarter update: Mason was spotted on the sideline coming out of the two-minute warning at the end of the second quarter. His status remains uncertain, but he is still in pads and uniform and was wearing his helmet, so the 49ers likely are hoping he will return in the third quarter.

3rd quarter update: Mason returned to the game to start the third quarter, but then left after only one play. He rushed for nine yards and then came off for Guerendo. After Mason left, the 49ers ran eight players en route to a touchdown and Guerendo was spelled on two plays by Patrick Taylor. The 49ers took a 23-3 lead on that drive. Even if Mason recovers sufficiently, he’s likely done for the night.