WEST LAFAYETTE, Indiana (Ticker) -- Stacey Dales hit three free throws in the final 41 seconds as No. 5 Oklahoma rallied to upset fourth-seeded and defending national champion Purdue, 76-74, in a second-round East Region contest.
Oklahoma (25-7) trailed by as many as 17 points and 14 in the second half but came back to clinch its first "Sweet 16" berth. The Sooners will face top seed Connecticut in the regional semifinals on Saturday in Richmond, Virginia.
Camille Cooper drilled two straight jumpers as the Boilermakers (23-8) led 72-67 with 2:28 left, but Oklahoma scored the next nine points to open a four-point lead.
LaNeishea Caufield and Jadrea Seeley each made baskets and Caufield added two free throws with 66 seconds left to put Oklahoma ahead, 73-72.
Dales added two free throws with 41 seconds to play for a three-point lead. Purdue's Katie Douglas missed a 3-pointer and Cooper grabbed an offensive rebound, but stepped on the baseline.
Dales nailed one free throw with 21 seconds left as the Sooners improved to 4-2 all-time in the NCAA Tournament. They shot 59 percent (16-of-27) in the second half and outscored Purdue, 44-30.
The Boilermakers had their seven-game home winning streak in the NCAA Tournament snapped and failed to reach their third-straight "Sweet 16" for the first time since 1990-92.
It is the quickest NCAA Tournament exit for a defending champion. Old Dominion won the 1985 championship but did not qualify the following year.
Purdue topped Duke last season to win its first national title but lost coach Carolyn Peck as well as stars Stephanie McCarty and Ukari Figgs to the WNBA.
Caufield scored 23 points, Dales poured in 16 and Phylesha Whaley and Caton Hill added 11 apiece for Oklahoma. Caufield shot 9-of-13 from the floor to help the Sooners shoot 47 percent (28-of-60).
Cooper scored 34 points on 13-of-18 shooting and Shinika Parks added 22 for the Boilermakers, who had their six-game winning streak snapped.
Cooper netted eight points during a 16-7 run as Purdue opened a 42-25 lead with 3:48 remaining in the first half.