The Wildcats went to Durham, N.C. Saturday as road underdogs and knocked off the Duke Blue Devils, 19-10.
Another contributing factor to Northwestern's rise may very well have been Stanford's victory late Saturday night on the road at then-No. 6 USC. The Cardinal's upset of the Trojans caused many to take note of how good Northwestern might be. The Wildcats beat the Cardinal 16-6 in Week 1.
Northwestern is ranked ahead of both USC (19) and Stanford (21) in Week 4.
Northwestern is the third highest-ranked Big Ten team in the poll. Both Ohio State (1) and Michigan State (2) are in the top five. Wisconsin is the fourth Big Ten team in the top 25 at No. 22.
This is the highest Northwestern has been ranked since the week after its 40-30 loss to Ohio State in 2013.
Here's a look at the bottom portion of the Week 4 AP Poll:
Earlier Sunday, Northwestern came in at No. 19 in the USA TODAY Coaches Poll.