AUSTRALIA'S defending champion Samantha Stosur has been knocked out of the US Open in the quarter-finals by top seed Victoria Azarenka.
The Australian Open champion downed Stosur 6-1 4-6 7-6 (7-5) in a superb Flushing Meadows quarter-finals.
The defeat is likely to have Stosur dropping out of the top 10, but the world No. 7 was brave and inspiring after a horrid start.
Azarenka will face either French Open champion Maria Sharapova or Wimbledon finalist Marion Bartoli in the semi-finals.
Stosur was oh-so close, conjuring a mini match point in the 11th game of the deciding set, but Azarenka saved it with her one and only ace before clinching an epic victory in the tiebreaker.
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