After losing two straight games to teams from Texas, Oregon dropped out of the AP Top 25 for the first time all season.
The Ducks (4-3) received three votes, but that placed them behind 42 teams in the ranking. Arizona State is the lone Pac-12 team in the Top 25 at No. 20 while UCLA and Arizona also received votes.
Oregon opened the season ranked No. 14 and moved up one spot before dropping to No. 21. The Ducks were back up to No. 18 last week before losing 89-84 to Texas Southern and 65-61 at Houston.
The Ducks return to Matthew Knight Arena Saturday at 5 p.m. to play Nebraska-Omaha.