The Ducks have 45 of 60 first-place votes. Kansas State is No. 2 with 14 first-place votes. Notre Dame is third and received one first-place vote.
The Crimson Tide, which had been No. 1 for 10 straight weeks, dropped to fourth after a 29-24 loss to the Aggies in Tuscaloosa, Ala., on Saturday.
Texas A&M moved up six spots to No. 9.
The Ducks were last No. 1 in 2010. That was the first season in the history of the program that Oregon reached No. 1, and the Ducks spent seven weeks there and reached the BCS championship game, which they lost to Auburn.
No. 25 Kent State is ranked for first time since Nov. 5, 1973.