BEIJING (AP) Top-ranked Victoria Azarenka and No. 2 Maria Sharapova advanced to the China Open semifinals on Friday.
Azarenka defeated Romina Oprandi of Switzerland 6-2, 6-0, and Sharapova beat sixth-seeded Angelique Kerber when the German retired with a right foot injury while trailing 6-0, 3-0.
``I thought we played a high level of tennis the first set and a half, and even though the score line was 6-0, 3-0, there were many games that went to deuce,'' Sharapova said. ``She had a few break points and long games on her serve.
``I actually didn't see much of her injury. I was surprised she called the trainer and even more so when she retired quickly after that.''
Sharapova has not dropped a set at the China Open. The French Open champion will next face seventh-seeded Li Na of China, who beat third-seeded Agnieszka Radwanska of Poland 6-4, 6-2.
Azarenka, who won the Australian Open this year, converted all six break points she earned and will next play either ninth-seeded Marion Bartoli of France or Carla Suarez Navarro of Spain.
``I felt like I was playing well, and that's what gave me an advantage to go and play and have that score line after the match, but it wasn't easy,'' Azarenka said. ``Sometimes it's important to stay tough and have that concentration to make sure that you can win every ball and every point.''
In the men's quarterfinals, third-seeded Jo-Wilfried Tsonga of France defeated Mikhail Yozhny of Russia 6-3, 6-2. Tsonga, who had a walkover in the third round, had seven aces and saved both break points he gave away.
``I think it was a good thing because I played three sets the day before,'' Tsonga said. ``For me it's good to have some rest.''
Unseeded Florian Mayer also reached the semifinals when he beat Chinese wild-card Zhang Ze 6-3, 6-4.
Tsonga will next play either Sam Querrey of the United States or Feliciano Lopez of Spain. Mayer will take on either top-seeded Novak Djokovic of Serbia or Jurgen Melzer of Austria.