49ers RB Jordan Mason has sprained AC joint, day-to-day

SANTA CLARA, Calif. -- While it remains to be seen whether he will be ready for the Oct. 20 game against the Kansas City Chiefs, San Francisco 49ers running back Jordan Mason got some good news about his ailing left shoulder Friday.

Mason suffered a sprained AC joint in the shoulder in Thursday night's 36-24 win against the Seattle Seahawks, Niners coach Kyle Shanahan said. Mason will be day-to-day when San Francisco begins preparing for the Chiefs on Monday.

"We take it as good news," Shanahan said. "I mean it doesn't guarantee [next] week or anything. He does have an AC sprain, but it was positive that it wasn't worse than that. It'll be day-to-day and hopefully he'll be good for the game but no guarantees."

Mason injured the shoulder with 9:37 left in the second quarter. After a 14-yard run, he landed hard on the shoulder on a tackle by Seahawks safety Julian Love. Mason walked to the sideline and stood there for a bit before making his way to the locker room.

Originally listed as questionable to return, Mason was back on the field for the first offensive snap of the third quarter. He gained 8 yards on a run to the right, but Shanahan said he could tell something didn't feel right and Mason went back to the sideline. He did not return to the game, though he was available in an emergency.

Rookie Isaac Guerendo and veteran back Patrick Taylor Jr. picked up the slack as the Niners rushed for 228 yards on 33 carries.

"I thought they both did a really good job," Shanahan said. "We didn't really miss a beat with it. They kept the whole rhythm of the offense going. They hit the right holes, they ran hard and made some plays for us, so they were prepared and didn't hesitate when they got their opportunities."

Mason finished with 73 yards on nine carries and caught a pass for 9 yards. His 609 rushing yards for the season leads the NFL as other runners get their sixth game to catch up this weekend. Mason also has three rushing touchdowns while stepping in for injured star running back Christian McCaffrey (Achilles tendinitis).

"Jordan's as tough as anybody, so I'm sure if he has a chance to play, he will," Shanahan said. "But [we] have to see how the shoulder responds."

Mason wasn't the only notable injury for the 49ers on Thursday. For the second game in a row, San Francisco had a kicker get hurt while trying to make a tackle on a kickoff return. Matthew Wright, who just signed with the team Tuesday, suffered a shoulder injury when attempting to bring down Seahawks returner Dee Williams with 1:17 left in the game. According to Shanahan, the shoulder "came out for a little bit" but went back in.

An MRI on Wright's shoulder came back negative on Friday, sources told ESPN's Adam Schefter. He is expected to be able to kick vs. the Chiefs next week. This means San Francisco is not expected to have to use three kickers in three games.

Wright signed with the Niners after kicker Jake Moody suffered a high right ankle sprain when trying to make a tackle against the Cardinals in Week 5. Moody is expected to miss multiple weeks. San Francisco brought in multiple kickers for tryouts last week before signing Wright. In addition to his perfect mark on field goals, he hit all three of his extra points against the Seahawks.