Victoria Azarenka of Belarus returns the ball during the women's singles quarterfinals against Samantha Stosur of Australia at the U.S. Open tennis tournament in New York, the United States, Sept. 4, 2012. Victoria Azarenka won 2-1 to enter the semifinals. (Xinhua/Wang Lei)

Victoria Azarenka of Belarus celebrates for victory after the women's singles quarterfinals against Samantha Stosur of Australia at the U.S. Open tennis tournament in New York, the United States, Sept. 4, 2012. Victoria Azarenka won 2-1 to enter the semifinals. (Xinhua/Wang Lei)

Victoria Azarenka of Belarus celebrates for victory after the women's singles quarterfinals against Samantha Stosur of Australia at the U.S. Open tennis tournament in New York, the United States, Sept. 4, 2012. Victoria Azarenka won 2-1 to enter the semifinals. (Xinhua/Wang Lei)

Victoria Azarenka of Belarus reacts during the women's singles quarterfinals against Samantha Stosur of Australia at the U.S. Open tennis tournament in New York, the United States, Sept. 4, 2012. Victoria Azarenka won 2-1 to enter the semifinals. (Xinhua/Wang Lei)

Victoria Azarenka of Belarus celebrates for victory after the women's singles quarterfinals against Samantha Stosur of Australia at the U.S. Open tennis tournament in New York, the United States, Sept. 4, 2012. Victoria Azarenka won 2-1 to enter the semifinals. (Xinhua/Wang Lei)

Victoria Azarenka of Belarus greets the audience after winning the women's singles quarterfinals against Samantha Stosur of Australia at the U.S. Open tennis tournament in New York, the United States, Sept. 4, 2012. Victoria Azarenka won 2-1 to enter the semifinals. (Xinhua/Wang Lei)

Victoria Azarenka of Belarus celebrates for score during the women's singles quarterfinals against Samantha Stosur of Australia at the U.S. Open tennis tournament in New York, the United States, Sept. 4, 2012. Victoria Azarenka won 2-1 to enter the semifinals. (Xinhua/Wang Lei)