World number four Victoria Azarenka of Belarus announced on Thursday that she pulled out of the ongoing China Open where she has reached the last 16.

Azarenka said: "It's disappointing to have to withdraw from China Open. I'm sorry to the fans. I was hoping that my foot would be OK, but it has been bothering me since Tokyo. I'm not sure about the recovery time yet, but I'll continue to consult with my doctor. I expect to be back for Luxembourg."

Her opponent Anastasia Pavlyuchenkova of Russia will benefit from the walkover to make the quarterfinals.

The China Open, which ran in its eighth year, has lost world number one Novak Djokovic, Maria Sharapova and the Williams sisters to injury or weird illness prior to the opening.

Second seed Gael Monfils of France and Russian veteran Mikolai Davidenko also announced decision to withdraw after the elite tournament kicked off last Saturday.

It was then followed by early upsets from reigning Grand Slam winners Li Na of China (French Open), Petra Kvitova of the Czech Republic (Wimbledon) and Australian Samantha Stosur (U.S. Open) in first two rounds.