Running back Jordan Mason left the game in the second quarter and was taken to the locker room for further evaluation. He returned briefly in the third quarter but couldn't continue and remained on the sidelines for the rest of the game.
"Jordan Mason, he had a shoulder AC sprain," Shanahan reported.
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Next week, the 49ers will begin preparing for their Week 7 matchup against the Kansas City Chiefs, and Mason's status remains uncertain.
"We take it as good news," Shanahan added. "I mean, it doesn't guarantee this week or anything. He does have an AC sprain, but it was positive that it wasn't worse than that. So he'll be day-to-day [next] week, and hopefully, he'll be good for the game, but no guarantees.
"... Jordan's as tough as anybody, so I'm sure if he has a chance to play, he will, but we've got to see how the shoulder responds. We're only a day out."
Mustapha is day-to-day
Tests on Friday confirmed that rookie safety Malik Mustapha sustained a low-ankle sprain, making his status day-to-day as well.
Another kicker injury
For the second consecutive game, a 49ers kicker sustained an injury. Newly-signed Matthew Wright left the game with a shoulder injury while attempting to make a tackle on a kickoff return, the same way regular kicker Jake Moody was injured on Sunday against the Arizona Cardinals.
"We're still waiting for his MRI to get back," Shanahan explained. "He did dislocate it—or it came out for a little bit. ... It went back in, but we've got to find out more on it when we get the MRI."
Shanahan expressed concern about Wright's availability for Week 7, saying, "We're not sure. I mean, we know he'll have a chance, but we won't know for sure until we get that MRI back."
If Wright's injury is more severe, the 49ers will once again bring in kickers for tryouts.
Other injury updates
Shanahan also provided updates on the following players who didn't participate against the Seahawks:
- DT Jordan Elliott is continuing to rehab his knee injury. The 49ers will re-evaluate him early next week.
- The 49ers hope LB Demetrius Flannigan-Fowles, who has been dealing with a half injury, will return to practice next week.
- CB Charvarius Ward, who did not play against the Seahawks due to a bruised knee, is considered day-to-day.
The coach also confirmed that the 49ers would open rookie wide receiver Ricky Pearsall's practice window next week, giving the team 21 days to activate him from the non-football injury (NFI) list once that officially occurs. However, running back Christian McCaffrey's practice window will remain closed for now.
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