Anderson dished off three assists and made two blocks while Matt Pilgrim ended with 18 points and six rebounds for the Cowboys (20-8, 8-6 Big 12), whose win over the nation's top-ranked team sparked a joyous post-game celebration by fans in Stillwater, Okla.
Obi Muonelo chipped in with 17 points and Keiton Page contributed 15 in Oklahoma State's win, its first over a No. 1-ranked team since Feb. 4, 1989 against Oklahoma.
Kansas (27-2, 12-1) saw its quest for a perfect conference season end and its 13-game winning streak snapped. Sherron Collins scored 22 points and Xavier Henry contributed 17 for the Jayhawks in the defeat.