ISTANBUL, Oct. 26 (Xinhua) -- Li Na, Victoria Azerenka, and Vera Zvonareva saw off their opponents Wednesday in the round robin stage of the season-ending TEB BNP Paribas WTA Championships in Turkey's largest city Istanbul.

In the first game of the evening Azerenka marked her first appearance in this year's tournament with a comfortable 6-2, 6-2 win over Samantha Stosur, who looked out of sorts after her impressive victory over Maria Sharapova on Tuesday.

Li Na took to the court in Istanbul for the first time Wednesday and earned a hard-fought 7-6, 6-4 victory over Sharapova in straight sets, virtually sealing the exit from the tournament of the world No. 2 player.

The final game of the evening saw Zvonareva overcome Caroline Wozniacki 6-2, 4-6, 6-3 in three sets to record her first win of the tournament.

The WTA's year-end finale, being held at Istanbul's Sinan Erdem Dome on indoor hard courts from Oct. 25-30, features the world's top eight singles players and top four doubles teams competing for the coveted title and a share of the 5 million U.S. dollars in prize money.

The round robin stage consists of two groups in the single's category with the top two from each group progressing to the semifinals.

The White group features Maria Sharapova (Russia), Victoria Azarenka (Belarus), Li Na (China) and Samantha Stosur (Australia) while the Red group features Caroline Wozniacki (Denmark), Petra Kvitova (Czech Republic), Vera Zvonareva (Russia) and Agnieszka Radwanska (Poland).

The competition also attracts the doubles teams of Kveta Peschke/Katarina Srebotnik, Liezel Huber/Lisa Raymond, Gisela Dulko/Flavia Pennetta and Vania King/Yaroslava Shvedova.

France's Marion Bartoli and Germany's Andrea Petkovic are also in Istanbul as singles alternates.