In the night match, Clijsters eliminated eighth-seeded Russian Anastasia Myskina 6-2, 6-2 in 56 minutes for her third straight rout in three days.
In the Belgian's three matches thus far, Clijsters has lost a total of eight games.
Sugiyama reached the semifinals with a 6-1, 6-3 victory against Slovak qualifier Tina Pisnik.
In doubles, 46-year-old Martina Navratilova and 17-year-old Svetlana Kuznetsova earned a semifinal berth by defeating Liezel Huber and Magdalena Maleeva 7-6 (6), 6-1.
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