Sania Mirza of India (L) and Cara Black of Zimbabwe in action during a doubles final match at the BNP Paribas WTA Finals 2014 at the Singapore Indoor Stadium, in Singapore, 26 October 2014. EPA/WALLACE WOON

Cara Black of Zimbabwe in action during a doubles final match at the BNP Paribas WTA Finals 2014 at the Singapore Indoor Stadium, in Singapore, 26 October 2014. EPA/WALLACE WOON

Cara Black of Zimbabwe (L) and Sania Mirza of India react after their win against Peng Shuai of China and Hsieh Su-Wei of Taiwan during a doubles final match at the BNP Paribas WTA Finals 2014 at the Singapore Indoor Stadium, in Singapore, 26 October 2014. EPA/WALLACE WOON

Hsieh Su-Wei of Taiwan (L), Peng Shuai of China (C), Cara Black of Zimbabwe (2-R) and Sania Mirza of Indi (R) shake hands at the net after the doubles final match of the BNP Paribas WTA Finals 2014 at the Singapore Indoor Stadium, in Singapore, 26 October 2014. EPA/WALLACE WOON

Sania Mirza of India (L) and Cara Black of Zimbabwe (R) hold up the Martina Navratilova trophy, after the doubles final match at the BNP Paribas WTA Finals 2014 at the Singapore Indoor Stadium, in Singapore, 26 October 2014. EPA/WALLACE WOON