India's Leander Paes and his Czech partner Radek Stepanek will lock horns with the Austrian-Slovakian pair of Julian Knowle and Filip Polasek in the Men's Doubles quarterfinals of the US Open Tennis tournament, taking place in New York. In the pre-quarterfinals, the fifth seeded Indo-Czech duo had defeated the Aussie-American combination of Jesse Levine and Marinko Matosevic, 6-1, 6-3.Meanwhile, Leander Paes and Sania Mirza, with their respective partners, have crashed out from the Mixed Doubles category. In the quarterfinals yesterday, the third seeded Indo-Russian duo of Leander Paes and Elena Vesnina lost to the lower ranked Czech pair of Frantisek Cermak and Lucie Hradecka, 6-7, 5-7; while Sania and his English partner Colin Fleming lost to the Polish-Czech combination of Marcin Matkowski and Kveta Peschke, 3-6, 5-7.In yesterday's other results, Swiss Roger Federer, Briton Andy Muray, Serena Williams of the United States and Agnieszka Radwanska of Poland advanced to their respective Singles categories.