Even during its bye week, Northwestern moved up a spot in each of the national rankings, jumping to 15th in the Coaches Poll and 16th in the AP Poll. Oklahoma State's loss to West Virginia allowed the Wildcats to move up a spot in each poll, staying put as the second-highest Big Ten team in each one.
The top-ranked Big Ten team in each poll? Ohio State — NU's opponent this week. The Buckeyes come in at No. 3 in the Coaches Poll and No. 4 in the AP Poll.
From the quick research I did, this looks like the best matchup at Ryan Field, rankings-wise, since No. 12 Penn State visited No. 6 Northwestern in 1995. You could certainly make an argument that this game is even bigger from a rankings standpoint. It's also one of the two biggest games on Saturday (Stanford at Washington is very similar, rankings-wise).
One thing is for sure: this is the last consecutive Saturday that NU has small jumps in the rankings. The Wildcats will either shoot up or fall a few spots depending on Saturday's results.