Oregon, coming off a 42-6 blowout of Stanford, moved up one spot to No. 8 in the Associated Press poll but stayed at No. 9 in the coaches poll.
Poll voters dinged USC after barely holding on to beat unranked Colorado 48-41. It came a week after Oregon crushed the Buffaloes in Eugene.
The Trojans dropped to No. 9 in the AP and No. 7 in the coaches poll.
The Washington Huskies stayed No. 7 in the AP and No. 8 in the coaches poll after beating Arizona 31-24, setting up a huge top-10 matchup against Oregon in Seattle on Oct. 14. Both teams will have their byes next week.
Oregon State bounced back from their first loss of the season to beat then No. 10 Utah in Corvallis, 21-7, on Friday.
The Beavers moved up four spots to No. 15 in the AP poll and five spots to No. 16 in the coaches poll.
USC also fell to No. 7 in the coaches poll.
Half of the Pac-12 is represented in the top 25 polls through five weeks, with both Oregon and Washington schools plus USC and Utah.
Washington State moved up three spots in both polls (No. 13 AP; No. 14 coaches) ahead of next week’s game against UCLA.
Utah dropped eight places in the AP to No. 18 and nine spots in the coaches poll to No. 19.