The former champion Svetlana Kuznetsova has been knocked out of the U.S. Open in the fourth round, beaten 7-5 7-6 by unseeded Slovakian Dominika Cibulkova.
Eleventh seed Kuznetsova, champion in New York in 2004 and runner-up in 2007, led by a break of serve in both sets but lost her way with 42 unforced errors as Cilbulova reached the U.S. Open quarter-finals for the first time.
