Canadian tennis star Eugenie Bouchard has filed a lawsuit against the United States Tennis Association claiming negligence after she slipped and hit her head in the locker room during the US Open.

The 21-year-old from Montreal said she slipped and fell from a “slippery, foreign and dangerous substance” in a locker room, forcing her to withdraw from the final Grand Slam tournament of the year, ESPN reported.

Bouchard, a 2014 Wimbledon finalist, is Canada’s biggest women’s tennis star and was ranked 25th in the world prior to the September 4 incident.

In the lawsuit, filed in US District Court in New York, Bouchard said she suffered a severe head injury that caused her to step away from the WTA Tour.

Bouchard slipped after her third-round victory over Dominika Cibulkova, falling backward and landing on the back of her head. She was forced to withdraw from tournaments in Tokyo and Wuhan, China as well.

“I thought I was physically ready, but unfortunately, the symptoms of my concussion came back,” Bouchard said after the Wuhan withdrawal. “I hope to get well soon and look forward to returning next year.”