Gael Monfils of France in action against Tomas Berdych of the Czech Republic during their match of the International Premier Tennis League (IPTL) in Singapore, 03 December 2014. The IPTL, which features four teams made out of a hybrid mix of current and former men’s and women’s players, is on its second leg in Singapore, after starting in the Phillipines, and will continue in New Delhi and conclude in Dubai. EPA/WALLACE WOON

Ana Ivanovic of Serbia in action against Serena Williams of the USA during an International Premier Tennis League (IPTL) match between the Micromax Indian Aces and the Singapore Slammers at the indoor stadium in Singapore, 03 December 2014. The IPTL is on its second leg in Singapore, after starting in the Phillipines, and will continue on in India and then Dubai. The league features four teams made out of a hybrid mix of current and former men’s and women’s players. EPA/WALLACE WOON

Ana Ivanovic of Serbia in action against Serena Williams of the USA during an International Premier Tennis League (IPTL) match between the Micromax Indian Aces and the Singapore Slammers at the indoor stadium in Singapore, 03 December 2014. The IPTL is on its second leg in Singapore, after starting in the Phillipines, and will continue on in India and then Dubai. The league features four teams made out of a hybrid mix of current and former men’s and women’s players. EPA/WALLACE WOON

Serena Williams of the USA in action during the mixed doubles match at the International Premier Tennis League (IPTL) in Singapore, 02 December 2014. The IPTL, which features four teams made out of a hybrid mix of current and former men’s and women’s players, is on its second leg in Singapore, after starting in the Phillipines, and will continue in New Delhi and conclude in Dubai. EPA/WALLACE WOON

Ana Ivanovic (L) of Serbia and Sania Mirza (R) of India joke during the International Premier Tennis League (IPTL) matches in Singapore, 03 December 2014. The IPTL, which features four teams made out of a hybrid mix of current and former men’s and women’s players, is on its second leg in Singapore, after starting in the Phillipines, and will continue in New Delhi and conclude in Dubai. EPA/WALLACE WOON