Quarterback Brock Purdy and defensive end Nick Bosa are not available for the San Francisco 49ers as they enter Green Bay with designs on finding their finishing kick on Sunday afternoon.

Purdy is out with a right shoulder injury and won't leave the sideline at Lambeau Field, head coach Kyle Shanahan said Friday. Shanahan also declared Bosa out and confirmed journeyman Brandon Allen would make his 10th career start at quarterback.

"Outside of here people haven't seen a lot of Brandon. But it's his second year (with the 49ers)," Shanahan said. "Obviously guys want Brock up, but guys are excited to see Brandon play."

Shanahan said the 49ers are "a little surprised" Purdy experienced tightness and discomfort in his shoulder after an MRI exam on Monday that showed no long-term cause for concern.

"The way it responded this week, it's really up in the air for next week," Shanahan said of Purdy's long-term prognosis.

Allen's most recent NFL start on the road was with the Cincinnati Bengals at the Baltimore Ravens in 2020. Allen completed 6 of 21 passes for 48 yards with two interceptions. He finished with a passer rating of 0.0 in a 38-3 loss.

"It's definitely an opportunity for me to go out and play well and put our guys in a good position to win the game," Allen said Friday. "And obviously we want Brock back and healthy and all that, but for time being, it is an opportunity for me."

Purdy took the practice field Thursday with the intent to participate. His shoulder tightened significantly, and the 49ers ushered him off the field to meet with trainers.

Purdy beat the Packers in the NFC divisional playoffs at San Francisco in January, but Allen is familiar to Packers head coach Matt LaFleur.

LaFleur was an assistant coach with the Rams during Allen's two-year run in Los Angeles. Allen broke into the NFL in 2016 with the Jacksonville Jaguars and is 2-7 in nine career starts. He went 1-2 with the Denver Broncos in 2019 and 1-5 in six starts over two years with the Bengals in 2020 and ‘21.

A victory against the visiting 49ers on Sunday would bolster the Packers' playoff chances, send a conference rival below .500 and avenge a bitter playoff defeat.

Those seemingly rank in no particular order for the Packers (8-3), although they don't shy from living at least partially in the past ahead of a Week 12 showdown.

San Francisco eliminated Green Bay 24-21 in the NFC divisional playoffs last season, scoring 10 unanswered points in the fourth quarter.

"That's what you've got to sit with all offseason, is going back, watching the game, trying to see what you could have done better," Packers quarterback Jordan Love said. "What you could have done differently in that game. ... Just knowing that's the team that knocked us out, we're definitely hungry for this game."

Ditto for San Francisco. The 49ers fell to 5-5 after last week's 20-17 home loss to the Seattle Seahawks, done in by Geno Smith's 13-yard touchdown run with 12 seconds to play.

Still only a game behind NFC West-leading Arizona, the reigning conference champion 49ers are just 1-3 in division play and can ill afford to lose more ground.

A visit to the AFC East-leading Buffalo Bills awaits after the trip to Green Bay.

While they're dealing with plenty of not-so-good news on the injury front, the 49ers do anticipate the return of George Kittle. The tight end does not carry an injury designation and is eager to play after a nagging hamstring injury sidelined him against the Seahawks.

"Very excited," Kittle said. "Can't pass up playing the Packers, so no, I will be out there for sure."

While Kittle likely will play on Sunday, cornerback Charvarius Ward has been ruled out and will miss his third game following the death of his 1-year-old daughter. Linebacker Tatum Bethune (knee), defensive lineman Kevin Givens (groin) and wide receiver Jacob Cowing (concussion) also have been ruled out, while offensive tackle Trent Williams (ankle) and offensive lineman Jon Feliciano (knee) is questionable.

As for the Packers, cornerback Jaire Alexander (knee) and linebacker Edgerrin Cooper (hamstring) have been ruled out and defensive end Colby Wooden (shoulder) is questionable for Sunday's game.

Allen was a three-year starter at Arkansas but has been a journeyman backup since entering the NFL in 2016 as the 201st overall pick of the Jaguars.

Shanahan and LaFleur have been fierce competitors since twice working together, first as low-level assistants with the Houston Texans in 2008, then on the so-called "dream team" staff in Washington that also included Sean McVay, Mike McDaniel and Raheem Morris; and two seasons with the Atlanta Falcons (2015, 2016) where LaFleur was quarterbacks coach and Shanahan called the plays.

Shanahan scored the most recent win over LaFleur in January. Green Bay has won seven of the past eight regular-season meetings between the franchises.

But the familiarity and shared-brain approach to offense that has the coaches completed each other's play calls has led to some tight games. The past three at Lambeau Field were all decided by three points.

Green Bay, which hosts a home game on Thanksgiving next Thursday, is starting a run of three games in 12 days. They'll play back-to-back Thursday games. Their Week 14 game is at Detroit.

That might make it good news for LaFleur that surprising contributors have emerged of late.

Packers wideout Christian Watson had a career-best 150 receiving yards on only four catches during last week's 20-19 road win against the Chicago Bears. His diving 60-yard reception in the fourth quarter put the Packers in position for Love's go-ahead, 1-yard scoring run with 2:59 to play.

Watson entered the game with eight catches for 83 yards over his previous three contests, but LaFleur assured Watson remains a "big part" of the attack.

"He's a guy who's got every measurable known to man in terms of the size, the speed, and it's not like those were easy plays he was making," LaFleur said. "He was making tough, contested catches."

San Francisco will aim to generate more pressure against Love than the Bears, who sacked him just once. The 49ers collected four sacks against the Seahawks, with Bosa and Leonard Floyd contributing 1.5 apiece.

Recent regular-season history between the Packers and 49ers at Lambeau Field has favored Green Bay.

The Packers have won seven of their past eight home games against the 49ers and are 22-11 versus San Francisco at home all-time. Green Bay leads the series 34-28-1.

--Field Level Media