Defending champion Juan Del Potro of Argentina advanced into the last eight over 2004 winner Hewitt 4-6, 6-3, 7-6 (7-2) as the Australian, 28, prepares for the US Open starting in just more than three weeks.

Fourth-seeded Fernando Gonzalez put out American Wayne Odesnik 6-2, 6-4 while French Open finalist Robin Soderling of Sweden, seeded fifth, stopped Frenchman Marc Gicquel 7-5, 5-7, 6-3.

Czech eighth seed Tomas Berdych eliminated German Philipp Petzschner 4-6, 6-3, 6-3.

German 10th seed Tommy Haas won a battle of veterans against Spain's Juan Carlos Ferrero 7-5, 2-6, 6-1 while 11th seed Ivo Karlovic of Croatia advanced against Indian qualifier Somdev Devvarman 7-5, 6-1.