Kansas State edged Oklahoma 87-85 in overtime on Sunday at the Lloyd Noble Center to send the Sooners to their third straight defeat.
OU (12-13, 5-8 Big 12) lost starter Ana Llanusa in the first quarter as she walked to the locker room on crutches.
OU sophomore Taylor Robertson scored 27 points and was 4-8 from behind the arc, breaking the Sooners single-season record with her 116th triple of the year.
Freshman Gabby Gregory scored a career-high 20 points for OU. Madi Williams had 15 points and nine rebounds for the Sooners.
Kansas State (12-11, 6-6) got 31 points and 19 rebounds from Peyton Williams while 6-5 center Ayoka Lee added 14 points and 13 rebounds.