The San Francisco 49ers enter Week 13 in a position no team has found itself in this season.

San Francisco faces the Philadelphia Eagles in a rematch of last season's NFC Championship Game and goes into that road contest as a three-point favorite.

That status in a game with a 10-1 team that played in the Super Bowl last season is reflective of just how good the 49ers have been since returning from the bye and reeling off three successive dominant wins to improve to 8-3.

Vindicating their position as favorites will not be easy, though, and these five players have a critical role to play in them doing so.

QB Brock Purdy

Let's get the obvious one out of the way first. Purdy got five snaps on that fateful first drive before a hit from Haason Reddick saw him tear an elbow ligament and quickly end any realistic hope of a Niners win.

Purdy has hardly missed a beat since returning from surgery on that injury, and a run in which a worrying penchant for turnovers saw the Niners drop three in a row is a distant memory following his performances during their current win streak.

The final pick in last year's draft leads the NFL in basically every quarterback metric save for QBR (Dak Prescott leads the league by that measure) but, for many, a road game with the Eagles is the acid test that will reveal whether he deserves to be talked about among the best quarterbacks in the game.

It is unfair for one game to serve as such a referendum, but it's imperative the Niners get a strong performance from Purdy if they are to have a hope of securing the statement win of their campaign.

WR Deebo Samuel

Samuel this week stood. by his previous assessment of Eagles cornerback James Bradberry, whom he called "trash" in the days after the title game. 

The versatile wideout was one of the most vocal 49ers in the days after the playoff loss in expressing his view that the 49ers would have won with Purdy healthy, and he will be a central figure in their attempts to back up his assertions.

Last week in the Thanksgiving win over the Seattle Seahawks, Samuel had 94 yards from scrimmage and a touchdown as the 49ers tormented the Seattle defense by constantly moving Samuel and Christian McCaffrey around the formation and in an out of the backfield.

A similarly influential display against a vulnerable Eagles back seven would go a long way to ensuring Samuel's words do not prove misguided.

RB Christian McCaffrey

With a rushing touchdown against Philadelphia, McCaffrey can become only the third player in NFL history with 50 rushing touchdowns and 25 receiving scores. He would join Hall of Famers Marshall Faulk and Lenny Moore in achieving that feat.

Beyond that shot at history, McCaffrey once again has crucial role to play in tandem with Samuel in manipulating a vulnerable Eagles linebacking group with their relentless motion. 

Kyle Shanahan this week said McCaffrey deserves to be in the MVP conversation. By producing a decisive performance and helping his head coach successfully put the Eagles linebackers in hell, McCaffrey can prove that opinion accurate.

DE Nick Bosa

Bosa has arguably his toughest assignment of the season as the reigning Defensive Player of the Year goes against veteran Eagles right tackle Lane Johnson.

A pass rejuvenated by the addition of Chase Young at the trade deadline has been on a tear, racking up 15 sacks in the last three games, and it's imperative they early and often against the Eagles' vaunted offensive line.

San Francisco has struggled defending third and short this season and, in the Eagles, the 49ers are taking on the best short-yardage team in the NFL, one that only needs nine yards on the first three downs because of the consistent success of their fabled fourth-down play.

Simply put, the 49ers' pass rush needs to ensure the Eagles are behind the chains as much as possible. Young, Javon Hargrave and Arik Armstead will all have their part to play, but this is a game where the focus will be on Bosa to deliver a reminder of why he was named the best defensive player in the game at the end of last season.

S Ji'Ayir Brown

Rookie third-round pick Brown was impressive in his first start on Thanksgiving against the Seahawks, drawing plaudits from defensive coordinator Steve Wilks.

Wilks said of Brown: 

"I thought Ji’Ayir did a great job. It was nothing glaring that I felt like he was out of place. Again, I felt confident with [S Tashaun] Gipson [Sr.] back there, along with [LB] Fred [Warner] and the guys that we surrounded him with, that he was going to do well. He’s doing a great job with his communication. We saw that yesterday in practice, just being assertive in certain things on the backend. I feel very confident when I can hear and see that."

That communication will be paramount against an Eagles offense that puts a lot of stress on safeties with its diverse run game with quarterback Jalen Hurts a central threat. 

The proficiency of that run game sets up the RPO game and weaponizes the play-action attack. Brown will have a lot more to think about than he did against Seattle, and the 49ers' confidence in him as a long-term starter

The 49ers believe they have a long-term starter in Brown, and their confidence in that belief will increase significantly if he handles the huge amount on his plate in his second start.

How to watch and stream 49ers-Eagles in Week 13

The Niners get their shot at revenge.