Chinese tennis star Peng Shuai is missing: Here's what you should know

The mystery surrounding the whereabouts of Ms Peng Shuai deepened on Thursday (Nov 18) after Chinese state media published an e-mail purportedly from the Chinese tennis star.

Ms Peng alleged on Nov 2 on the Twitter-like Weibo that she had been "forced" into sex by former vice-premier Zhang Gaoli during a long-term on-off relationship, but the post was swiftly deleted.

The 35-year-old Ms Peng has not been seen since.

But who is Ms Peng Shuai?

Doubles number one

Ms Peng is one of China's biggest sports stars, winning the women's doubles at Wimbledon in 2013 alongside Taiwan's Hsieh Su-wei for her first Grand Slam title.

A second followed at the French Open in 2014 - again with her long-time friend Hsieh - and Ms Peng spent 20 weeks that year ranked number one in doubles.

Where is Peng now?

Ms Peng has not been seen since she made the Weibo post.

Chinese state broadcaster CGTN on Thursday posted a letter attributed to Ms Peng on its Twitter account.

"I am not missing, nor am I unsafe. I've just been resting at home and everything is fine," the letter said, adding that her purported allegations of sexual assault were "not true".

But the effort to knock down her allegations of an affair with the former Communist Party leader was met with scepticism from supporters.

What did she say?

Ms Peng alleged in a post that following Mr Zhang's retirement, he and his wife invited Ms Peng over for a meal. Mr Zhang then pressured Ms Peng to have sex, it said.

"That afternoon I didn't agree at first and kept crying," the post said.

Ms Peng eventually agreed to an affair with Mr Zhang, but said in her post that she was angered about his insistence on the relationship being kept secret.

"I know I can't say it all clearly, and that there's no use in saying it," the post said. "But I still want to say it."

"I know that for someone of your eminence, Vice-Premier Zhang Gaoli, you've said that you're not afraid," Ms Peng wrote in her post, "but even if it's just me, like an egg hitting a rock, or a moth to the flame, courting self-destruction, I'll tell the truth about you."

What was the response to her allegations?

Ms Peng's post was soon deleted, but not before social media users took screenshots.

Those have been censored on China's heavily vetted Internet.

But Ms Peng's allegation was posted to Twitter - which is banned in China - allowing it to reach a worldwide audience.

Ms Peng still comes up on search results online in China, but her allegations do not, and searches for her and Mr Zhang together also show up nothing.

International pressure had been mounting for China to clarify Ms Peng's safety.

Grand Slam champions Novak Djokovic, Naomi Osaka and Chris Evert expressed concern over her case this week, while WTA head Steve Simon called for an investigation into her allegations.

He separately told The New York Times the group might reconsider its operations in China, including 11 tournaments, if it did not see a sufficient response.

Mr Simon dismissed the CGTN letter as unsatisfactory. "I have a hard time believing that Peng Shuai actually wrote the e-mail we received or believes what is being attributed to her," he said in a statement.

Heart defect

Ms Peng was born in January 1986 in Xiangtan, in the central province of Hunan, to a father who was a policeman.

The city also happens to be the hometown of the founder of the People's Republic of China, Mao Zedong.

She grew up in an ordinary family, according to local media, and was introduced to tennis at the age of eight by her uncle, a former tennis coach.

Ms Peng's fledgling career was nearly cut short when doctors said she would need an operation to treat a heart defect at 12.

She insisted that the operation go ahead despite her family's concerns about undergoing the procedure at such a young age, because she "loved tennis too much", she once said.

She travelled alone to the United States at 15 to further her training, armed only with an electronic dictionary.