Serena Williams and Maria Sharapova have withdrawn from the China Tennis Open on the eve of the tournament's opening match.
The men's competition in Beijing also suffered a major setback earlier this week when world number one Novak Djokovic pulled out with a back injury.
World number two Sharapova twisted her ankle against Wimbledon champion Petra Kvitova in the Pan-Pacific Open quarter-finals on Thursday and was forced to quit the Tokyo tournament.
It's the second year in a row that former world number one Williams has pulled out of the Beijing event.
The tournament website says the American was due to arrive in the city on Friday but failed to show up.
Her absence means neither of the crowd-pulling Williams sisters will be in attendance after Venus said last month that she had been diagnosed with an autoimmune disease that causes fatigue.
There will now be added pressure on world number five Li Na to do well at the China Open which takes place during national holidays in the country.
The Chinese won this year's French Open, becoming the first player from an Asian nation to claim a grand slam singles title, but her form has since nosedived and she was knocked out in the first round of the US Open.
World number one and defending champion Caroline Wozniacki, third-ranked Victoria Azarenka and number four Vera Zvonareva are among the players vying for the $1 million first prize.
Former men's world number one Pete Sampras and Russian past master Marat Safin play an exhibition match to open the newly-built Centre Court at Beijing's National Tennis Centre which hosted the 2008 Olympics.