The San Francisco 49ers are under no illusions as to the test they will face on Christmas Day when they take on the Baltimore Ravens in a battle of 11-3 number one seeds.

San Francisco has reeled off six straight wins to catapult into the number one seed in the NFC, the 49ers averaging 34.5 points per game since their Week 9 bye as quarterback Brock Purdy has solidified himself as the MVP favorite.

But the 49ers' red-hot offense will be sternly tested by the Baltimore defense, which leads the NFL with 50 sacks for negative yardage.

As such, Shanahan was asked on Thursday if the primetime matchup will be a huge challenge for Purdy "from the shoulders up", with the second-year signal-caller's renowned ability to process information pre and post-snap sure to receive a significant examination from Mike Macdonald's defense.

But Shanahan insisted it isn't just about Purdy, instead articulating the test the offense as a group must pass for the 49ers to move to 12-3 and within one win of clinching a first-round bye and homefield advantage in the playoffs.

Said Shanahan:

"I think it’s a big game for everybody because there’s not just one way in particular. They lead the league in sacks so right away you think about our O-Line and that is true because they have good pass rushers, but also that has a lot to do with how good our receivers do getting to their spots and getting open, Brock to get into the right spots, guys not getting re-routed so they can get there in time. When you play a sound good defense with good players all over, it’s a little bit of everything."

Last week, the 49ers' offensive line did not give up a sack as San Francisco clinched the NFC West title with a blowout win over the Arizona Cardinals, and Shanahan directed high praise to those in the trenches ahead of what figures to be a substantially more difficult assignment in front of a national audience.

"I think they’ve been great," Shanahan said. 

"When you look at our whole offense, just as far as running the ball and throwing the ball, you can’t do that stuff without a good O-Line, you can’t do that stuff without a good quarterback, you can’t do that stuff without good players that he’s throwing to. 

"The success of us throughout the year so far, there’s not one group that isn’t playing at a high level."

It is difficult to dispute Shanahan's assessment of his offense and his team as a whole, which has fired on all cylinders this season save for a three-game losing streak prior to their bye. The 49ers have made light work of their biggest games this season, blowing out the Dallas Cowboys and the Philadelphia Eagles, doing the same to the Ravens would be their most remarkable statement yet.

49ers have huge issue hanging over their Christmas plans

It’s a massive concern