No. 1: Chris Carson vs. the 49ers run defense
With the 49ers transitioning to what was essentially a carbon copy of the Seahawks defense to a wide-9 alignment, the team has been vulnerable to the run this season in what is the flaw to an overall great defense.
San Francisco has allowed a 4.7 yards per rush average this season, which is 22nd in the NFL.
While not one of the elite running backs in the NFL, Chris Carson has done a good job running for the Seahawks with 764 yards for a 4.4 yards-per-attempt average and three touchdowns.
Not the best in the NFL, but not too shabby either.
The 49ers have been susceptible to conceding early touchdowns, due to the offense ramming the ball down their throats, but they will need to be hot early to stifle this.
A lot of this will fall on linebackers Fred Warner and Dre Greenlaw to hit the gaps on all three downs, while the defensive line should (on paper, at least) be able to make some inroads on the Seahawks offensive line.
Seattle will no doubt have noticed the 49ers’ vulnerability lately to the run, so San Francisco has to scheme to defend it and take out this part of Seattle’s offense.