Two clutch free throws each from Bryce Williams and Keylan Boone lifted host Oklahoma State to a 74-69 upset victory over No. 18 Texas Tech Monday in Stillwater, Okla., to give the Cowboys the season sweep of the Red Raiders.In another Big 12 Conference tilt chock full of plenty of March-like madness, the two teams went toe-to-toe and into overtime for the second time this season.Terrence Shannon Jr. and Mac McClung both missed 3-point attempts on the possession after Boone’s two makes and Williams corralled the long rebound and hit his foul shots to ice the win.Freshman Cade Cunningham led the Cowboys (15-6, 8-6 Big 12) with 20 points and came up with a key bucket and steal in overtime. Kalib Boone added 18 points and 7 rebounds.Shannon topped Texas Tech (14-8, 6-7) with 18, while McClung notched 17. But both were each 1-for-5 from 3-point range.The Red Raiders forged overtime with an alert play by Shannon. McClung missed a 3 with eight seconds to go in regulation, with Shannon tracking down a long rebound and then zipping a pass to Kyler Edwards for a layup with 2.8 seconds left.