NEW YORK -- Kemba Walker hit the winning basket on a classic stepback jumper at the buzzer, and Connecticut (No. 19 ESPN/USA Today) stunned third-ranked Pittsburgh 76-74 in the quarterfinals of the BIG EAST Championship presented by American Eagle Outfitters on Thursday. Walker got the ball at the top of the key with 15 seconds left, allowed the clock to melt under five, then made a move toward the basket. He used a crossover and shoulder roll to dump his defender, 6-foot-10 Gary McGhee, right to the ground, then calmly drained the shot. The buzzer sounded just as the ball went through the net, and Shabazz Napier was the first to grab Walker by the waist and hoist him into the air. The Huskies (24-9) have won three games in three days after a late-season slide sent them to the No. 9 seed in the tournament. They'll face St. John's or Syracuse in the semifinals Friday night.