The Ravens have managed to move the ball against some of the league's best defenders this season.

The 49ers pose a different type of challenge.

San Francisco has the league's No. 1 overall defense, allowing 248 yards per game, and also lead the NFL with 44 sacks. 

“A lot of high [draft] picks. They earned those picks," Ravens coach John Harbaugh said. "They're Top 5 picks, and they did a really good job. I give them a lot of credit. They decided that they were going to build a great defensive front with those picks they had, and they did it. And they all panned out. They're all good players." 

The 49ers have several players that can get to the quarterbacks. 

Arik Armstead leads the way with 10 sacks), followed by Nick Bosa (eight sacks) and Dee Ford (6.5 sacks). The loss of Matt Skura to a season-ending knee injury could be troublesome for Baltimore. Skura had started 29 consecutive games and was No. 2 in Pro Bowl voting. Undrafted rookie Patrick Mekari will take his spot.

San Francisco second-year linebacker Fred Warner was named the NFC Defensive Player of the Week after notching 11 solo tackles, a sack, two hurries, nine total stops and a forced fumble in a 37-8 victory over the Green Bay Packers. 

“I think we have one of the better pass rushes in the league, which helps every defense," 49ers coach Kyle Shanahan said in a conference call with Baltimore media. "Most teams that have that type of front four – and can get to the quarterback with a front four – are usually up there defensively on the year. 

"Then when you add in our secondary and sound coverages we have, and some of the players on our back end, the way we’ve been able to mix some stuff up while still staying sound, I think it’s allowed us to get a huge jump this year.”

The 49ers will also face their biggest challenge against Ravens quarterback Lamar Jackson, who is having an MVP-caliber season. Jackson leads the team with 876 yards rushing. He has also thrown for 2,427 yards with 24 touchdowns and five interceptions.

Jackson also knows that he faces a daunting challenge. 

“Speed – all 11 to the ball, that popped out on the screen, and their front four is dangerous," Jackson said about looking at film on San Francisco. "They've been No. 1 in almost all aspects, statistical-wise, and it shows on film.”

Jackson was named the AFC Player of the Week for the fourth time this season. completed 15 of 20 passes (75.0 percent) for 169 yards, five touchdowns and no interceptions for a 139.4 passer rating in the Ravens’ 45-6 win over the LA Rams. He also ran for 95 yards on eight carries.

The Ravens are 5.5-point favorites.