The San Francisco 49ers will face the 7-3 Green Bay Packers on the road without their starting quarterback. QB1 Brock Purdy (right shoulder) was ruled out of the team’s Week 12 game after being a limited participant in practice on Wednesday and Thursday and not attending Friday’s practice at all. The 49ers’ third-year quarterback suffered his right shoulder injury during San Francisco’s Week 11 game against the Seattle Seahawks.

“I don’t want to say there’s any long-term concerns. We got the MRI on Monday, we really thought he needed some rest,” head coach Kyle Shanahan said Friday. “We weren’t really worried about him not being good this week, but when he started on Thursday it surprised him, it surprised us how (his shoulder injury) felt. So we had to shut it down.

“I really don’t know what to think. The MRI doesn’t look like that, so it should be fine. But the way he responded, it’s really up in the air for next week. We’ll have to see on Monday. “

Since making his first start for the 49ers in Week 14 of the 2022 season, Purdy has missed just one game: the 2023 regular season finale against the Los Angeles Rams. With Purdy out of the lineup against the Packers, ninth-year pro Brandon Allen will lead the 49ers offense at Lambeau Field on Sunday.

Allen was named the 49ers’ backup quarterback in September. He has made a total of nine starts in his NFL career, with his most recent start coming in the final game of the 2021 season as a member of the Cincinnati Bengals. In that game, Allen connected on 15 of 29 pass attempts for 136 yards and a touchdown in the team’s close loss to the Cleveland Browns.

Defensive lineman Nick Bosa, who missed all three practices this week due to a hip/oblique injury, also was ruled out Sunday. Meanwhile, left tackle Trent Williams enters the weekend as questionable.