New York - Dominika Cibulkova of Slovakia reached the quarter-finals of the US Open on Monday with a 7-5, 7-6 (7/4) win over Svetlana Kuznetsova of Russia.
Unseeded Cibulkova will play either top seed Caroline Wozniaki of Denmark or former champion Maria Sharapova of Russia for a place in the semi-finals.
An upset winner here in 2004 when she was just 19-years old, Kuznetsova added the French crown to her Grand Slam collection last year, but this year she has struggled with injuries and inconsistent form.
She grabbed an early break against Cibulkova, at 45th the lowest-ranking player left in the women's draw.
The Slovakian, however, quickly broke back and when Kuznetsova double-faulted at break point in the 12th game she took the first set 7-5.
The second set followed a similar pattern with Kuznetsova taking an early break and a 3-1 lead, only for Cibulkova to get back on level terms at 3-3.
The Slovakian served for the match and had two match points on her serve at 5-3 ahead, but squandered them with two unforced errors to allow a lifeline for Kuznetsova.
That lasted as far as the tie-break, which Cibulkova dominated from the start winning it on her fourth match point to reach a Grand Slam quarter-final for just the second time after the 2009 French Open.