The Blue Devils are 15-6 and have lost four of five, including two home games. They had been in every men's basketball poll since the preseason rankings of 2007-08, a streak of 167 weeks that was the fifth-longest run since the AP poll debuted in 1948-49. The record is UCLA's 221 straight polls from 1966 to 1980.
Oklahoma is 18-2 and was ranked No. 1 for the third straight week, receiving 45 first-place votes from the 65-member national media panel Monday. North Carolina is 19-2 and stayed second, with 20 No. 1 votes.
Duke being unranked comes two weeks after the school's women's basketball team exited the AP Top 25 for the first time since November 1999.
ESPN Stats & Information and The Associated Press contributed to this report.