World No. 2 Maria Sharapova and former top player Serena Williams pulled out of the China Open on Friday, one day before the beginning of the WTA premier event.

Sharapova twisted her ankle while serving Thursday and quit her Pan Pacific Open quarter-finals in Tokyo against Petra Kvitova.

The 24-year-old Russian said on her website, "Good news is that the MRI showed no big damage in the ankle. Will do my best to recover in time for Istanbul(the season-ending championships)."

"It better recover soon because I can become quite the annoying patient! I will keep everyone posted with my progress."

Serena Williams also missed the tournament due to injury. The American was out of tennis for almost a year with a series of injuries, but hit her form quickly after coming back, reaching her fifth US Open final earlier this month.

According to the official website of the China Open, Serena should have arrived in Beijing on Friday, however, she didn't appear in the women's singles draw, meaning she would be absent for the second consecutive year.

With the season nearing its end, a bunch of players have deleted the China trip from their schedule, world No. 1 Novak Djokovic quit the event due to a negative report from his latest physical check. Others absent included Richard Gasquet, Robin Soderling and Venus Williams.