Northwestern (8-2, 4-2 Big Ten) was leapfrogged by Houston (19), North Carolina (17) and Navy (16), but did jump ahead of Mississippi State (No. 17 last week).
Northwestern's strength of schedule likely took a hit when Duke lost to Pittsburgh and Stanford lost to Oregon in Week 11.
Ahead of Northwestern and Mississippi State in last week's rankings, almost everybody held serve. Teams 11 through 16 in last week's rankings all won. No. 10 Utah lost at Arizona, but only fell to No. 13.
At the top of the rankings, Clemson, Alabama, Ohio State and Notre Dame remained in the top four, with Clemson still at No. 1.
Elsewhere in the Big Ten, Iowa remained at No. 5. Michigan (12), Michigan State (9) and Wisconsin (25) also cracked the top 25.
Here are the full rankings:
No. 20 Northwestern plays on the road at No. 25 Wisconsin this Saturday (2:30 p.m. CT, Big Ten Network).