Kansas faces the challenge of holding onto its new No. 1 ranking in the AP Top 25 men's college basketball poll when it visits No. 18 Villanova this week. The Jayhawks are the fifth different team to reach No. 1 this season. Michigan State, Kentucky, Duke and Louisville were the others. None of them won more than two games before stumbling after claiming the top spot. This week's AP Top 25 national schedule also includes a marquee matchup between No. 5 Ohio State and No. 6 Kentucky in Las Vegas on Saturday.