Serena taking a winning start at WTA Championships Istanbul
In her opening match of the WTA Championships, world no.1 and the defending champion American Serena Williams overpowered German Angelique Kerber 6-3 6-1.
Williams, already guaranteed to end the season on top of the world rankings, is aiming to become the first player to successfully defend the season-ending title since Justine Henin in 2007 and win a fourth crown overall.
In another match, second seed Victoria Azarenka was made to work hard for a 7-6 (7-4) 6-2 victory over Italian world number seven Sara Errani.
Poland's Agnieszka Radwanska, seeded third, lost 6-4 6-4 to the Czech Republic's fifth seed Petra Kvitova.
Poland's Agnieszka Radwanska, seeded third, lost 6-4 6-4 to the Czech Republic's fifth seed Petra Kvitova.




