It’s been a topsy-turvy season in college basketball, with five teams having been ranked No. 1 through the first 18 polls. That should mean a wide-open NCAA Tournament. Week-by-week in the Associated Press poll:

Week 1* (Oct. 26): Indiana

Week 2 (Nov. 12): Indiana

Week 3 (Nov. 19): Indiana

Week 4 (Nov. 26): Indiana

Week 5 (Dec. 3): Indiana

Week 6 (Dec. 10): Indiana

Week 7 (Dec. 17): Duke

Week 8 (Dec. 24): Duke

Week 9 (Dec. 31): Duke

Week 10 (Jan. 7): Duke

Week 11 (Jan. 14): Louisville

Week 12 (Jan. 21): Duke

Week 13 (Jan. 28): Michigan

Week 14 (Feb. 4): Indiana

Week 15 (Feb. 11): Indiana

Week 16 (Feb. 18): Indiana

Week 17 (Feb. 25): Indiana

Week 18 (March 4): Gonzaga

*-Preseason poll