Freshman Jawun Evans had 22 points, eight assists and six rebounds to help Oklahoma State upset No. 3 Kansas 86-67 on Tuesday night.
The Cowboys beat Kansas in Stillwater for the third straight time and the fifth in seven years.
Jeff Newberry scored 13 points and Jeffrey Carroll added 11 for the Cowboys, who had lost four straight. Oklahoma State shot 50 percent from the field, made 11 of 21 3-point attempts and outrebounded the Jayhawks 38-31.
Frank Mason III scored 14 points and Perry Ellis added 13 for Kansas (15-3, 4-2 Big 12), which has lost two of its past three and fell out of a tie for the Big 12 lead.
Oklahoma State made 23 of 26 free throws while Kansas made just 13 of 24.
The Cowboys (10-8, 2-4) nearly knocked off then-No. 2 Oklahoma six days earlier, but they missed a last-second shot and lost 74-72.