Australia's US Open tennis champion Samantha Stosur has suffered a dramatic form reversal at the WTA Championships in Istanbul.
Following her breakthrough victory over Maria Sharapova yesterday, Stosur has crashed to a 6-2 6-2 loss to Victoria Azarenka from Belarus.
It was the Queenslander's fifth straight defeat to Azarenka, and it means she'll have to beat China's Li Na in her last round robin match to make the semi-finals.
