Top-seeded St Joseph's suffered last-gasp disappointment as the Oklahoma State Cowboys edged past them 64-62 at the NCAA tournament.
A John Lucas three-pointer with 6.9 seconds left booked the Cowboys an unexpected place in the "final four", where they will play Sunday's winner of the Kansas v Georgia Tech game.
St Joe's had a chance to force overtime but Jameer Nelson missed a shot at the buzzer.
In the day's other "elite eight" contest, Ben Gordon scored 36 points and Rashad Anderson 28 to lead Connecticut to an 87-71 win over Alabama.
Second seed Connecticut (31-6) dominated the first half, going up 53-29, and never lost control as they earned the right to play Duke or Xavier.
Duke are the only one of four top seeds left in the competition.