Tennis superstar Serena Williams took to social media Thursday (Nov. 18) to call for an investigation and to voice concern about the well-being of Chinese tennis player Peng Shuai, who disappeared after accusing a former high-ranking Chinese government official of sexual assault.

“I am devastated and shocked to hear about the news of my peer, Peng Shuai. I hope she is safe and found as soon as possible,” Williams tweeted. “This must be investigated and we must not stay silent. Sending love to her and her family during this incredibly difficult time. #whereispengshuai."

Peng Shuai, a French Open and Wimbledon doubles champion, accused retired Vice Premier Zhang Gaoli of coercing her into sex at his home three years ago, CBS News reported. She posted her allegation Nov. 2 on her social media account on Weibo, China’s Twitter-like platform. The post was deleted, and she hasn’t been seen since then.

Fellow superstar Naomi Osaka weighed in on the disappearance on Tuesday (Nov. 16) saying, “Censorship is never OK at any cost, I hope Peng Shuai and her family are safe and OK. I'm in shock of the current situation and I'm sending love and light her way."

On Sunday (Nov. 14), the WTA (Women’s Tennis Association) Tour urged the Chinese government to investigate and to end censorship of Peng Shuai, The Guardian reported. The association called for a “full, fair and transparent investigation into sexual assault allegations against the former Chinese leader.”

Meanwhile, several other notable current and former tennis stars have added their voices to the call for an investigation. Men’s no. 1 player  Novak Djokovic called her disappearance "shocking," and retired women’s star Chris Evert described the entire situation as "disturbing."