- WTA Championship
Azarenka secures year-end No. 1 ranking
Victoria Azarenka ensured she will begin 2013 as the world No. 1 by beating Li Na at the WTA Championship in Istanbul.
Azarenka, who booked a semi-final with Maria Sharapova, triumphed 7-6(4) 6-3 in one hour and 39 minutes.
Azarenka needed to avoid defeat in order to stave off the threat from Sharapova, the world No. 2, in the rankings.
Na claimed a break at 5-2 down in the second set as Azarenka threatened to wobble - but she held firm to remain on top of the world until the end of the year.
Maria Sharapova cruised past Sam Stosur in straight sets to finish top of the White Group with three wins from three.
She was already assured of her place in the last four but gained a morale-boosting 6-0 6-3 victory ahead of her semi-final clash against Azarenka.
Stosur, a late replacement for Petra Kvitova who was struck down by illness, looked out-of-sorts as she won just five points in the opening set and things did not get much better as Sharapova wrapped up victory inside 65 minutes.
Agnieszka Radwanska needed three and a half hours to get the better of Sara Errani and book a semi-final with Serena Williams. Radwanska, the world No. 4 who had won five of the previous six meetings between the two, eventually triumphed 6-7(8) 7-5 6-4.