Azarenka seals year-end top spot
Victoria Azarenka ensured herself the number one spot until the end of the year with a straight-sets win over Li Na in the WTA Championship.
The Belarus player and number one seed defeated her eighth-seeded Chinese opponent after being pushed hard in the opening set in Istanbul.
Azarenka went to take it on the tie-break before dominating the second set to win 7-6 (7/4) 6-3.
Maria Sharapova swept past Sam Stosur 6-0 6-3 but that was not good enough to take the number one ranking after Azarenka's win.
The Russian second seed made it three wins but was already qualified for the semi-finals before she faced Australian Stosur, who had replaced defending champion Petra Kvitova after the Czech Republic player withdrew with illness.
Agnieszka Radwanska of Poland reached the semi-finals when she edged Sara Errani of Italy 6-7 (6/8) 7-5 6-4 in a match that lasted three-and-a-half hours.
The fourth-ranked Radwanska will now play Serena Williams on Saturday after the American finished her three group matches undefeated.