Victoria Azarenka of Belarus returns a shot to Li Na of China during their tennis match on the fourth day of the WTA championship in Istanbul, Turkey, Oct. 26, 2012. Victoria Azarenka won the macth with 2-0. (Xinhua/Ma Yan)

Li Na of China returns a shot to Victoria Azarenka of Belarus during their tennis match on the fourth day of the WTA championship in Istanbul, Turkey, Oct. 26, 2012. Victoria Azarenka won the macth with 2-0. (Xinhua/Ma Yan)

Victoria Azarenka of Belarus returns a shot to Li Na of China during their tennis match on the fourth day of the WTA championship in Istanbul, Turkey, Oct. 26, 2012. Victoria Azarenka won the macth with 2-0. (Xinhua/Ma Yan)

Victoria Azarenka of Belarus endured to end 2012 as the world No. 1 by beating Li Na of China 7-6, 6-3 at the WTA Championships on Friday and booked a semifinal clash with Maria Sharapova of Russia.

"It feels great, a dream comes true," Azarenka said of her achievement after the match in a courtside interview.

"I want to play my last matches here and then enjoy being the world number one. I want to focus on this competition, there are still lots of challeges ahead."

In the other two matches on the final day of round-robin play, Sharapova swept past Samantha Stosur of Australia 6-0, 6-3 while Agnieszka Radwanska, the No. 4 seed from Poland, booked a semifinal with Serena Williams of the United States after defeating Italian Sara Errani 6-7, 7-5 and 6-4.