Petra Kvitova returns to Ana Ivanovic. Regi Varghese/AP
epa03591857 Roberta Vinci of Italy in action against Germany's Angelique Kerber during the third day of the Dubai Duty Free Tennis Championships in Dubai, United Arab Emirates, 20 February 2013. EPA/ALI HAIDER *** Local Caption *** 03591857.jpg
Jie Zheng in action against Caroline Wozniacki. Ali Haider/EPA
Yulia Putintseva reacts during her match against Agnieszka Radwanska. Ali Haider/EPA
epa03592000 Germany's Angelique Kerber returns the ball to Roberta Vinci of Italy during the third day of the Dubai Duty Free Tennis Championships in Dubai, United Arab Emirates, 20 February 2013. EPA/ALI HAIDER *** Local Caption *** 03592000.jpg
Nadia Petrova plays a forehand against Carla Suarez Navarro. Julian Finney/Getty Images
Ana Ivanovic in action against Petra Kvitova during day three of the Dubai Duty Free Tennis Championship. Julian Finney/Getty Images
The sun sets over the Dubai Duty Free stadium on day three of this year's WTA competition. Julian Finney/Getty Images
Sara Errani in action in her match against Sorana Cirstea. Julian Finney/Getty Images
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Sorana Cirstea of Romania faces off against Sara Errani Julian Finney/Getty Images.
Serena Williams faces the media after announcing she had pulled out of the Dubai Duty Free Tennis Championships through injury. Regi Varghese/AP
Petra Kvitova returns to Ana Ivanovic. Regi Varghese/AP
epa03591857 Roberta Vinci of Italy in action against Germany's Angelique Kerber during the third day of the Dubai Duty Free Tennis Championships in Dubai, United Arab Emirates, 20 February 2013. EPA/ALI HAIDER *** Local Caption *** 03591857.jpg
Jie Zheng in action against Caroline Wozniacki. Ali Haider/EPA
Yulia Putintseva reacts during her match against Agnieszka Radwanska. Ali Haider/EPA
epa03592000 Germany's Angelique Kerber returns the ball to Roberta Vinci of Italy during the third day of the Dubai Duty Free Tennis Championships in Dubai, United Arab Emirates, 20 February 2013. EPA/ALI HAIDER *** Local Caption *** 03592000.jpg
Nadia Petrova plays a forehand against Carla Suarez Navarro. Julian Finney/Getty Images
Ana Ivanovic in action against Petra Kvitova during day three of the Dubai Duty Free Tennis Championship. Julian Finney/Getty Images
The sun sets over the Dubai Duty Free stadium on day three of this year's WTA competition. Julian Finney/Getty Images
Sara Errani in action in her match against Sorana Cirstea. Julian Finney/Getty Images
162205662
Sorana Cirstea of Romania faces off against Sara Errani Julian Finney/Getty Images.
Serena Williams faces the media after announcing she had pulled out of the Dubai Duty Free Tennis Championships through injury. Regi Varghese/AP
Petra Kvitova returns to Ana Ivanovic. Regi Varghese/AP
