The United States Tennis Association (USTA) says it is not to blame for Eugenie Bouchard's fall at the US Open.
The Canadian world number 48 is suing the USTA for damages after suffering concussion at the Grand Slam in New York in September.
The USTA claim Bouchard should not have gone into the treatment room without "express consent of, or accompaniment of, authorised personnel".
Bouchard, 21, is seeking compensation for lost income and medical costs.
She withdrew from the US Open prior to a fourth-round match after the fall and pulled out of her comeback event at the China Open on 5 October because of dizziness.
The lawsuit alleges Bouchard slipped on "a foreign and dangerous substance" in New York and also claims that the injury has damaged her quality of life.
However, in its legal response to Bouchard's claims, the USTA claims that "as a highly ranked and/or seeded professional tennis player, the plaintiff was experienced and well-versed in the procedures and protocols of the women's tour" and "knew or should have known the procedures and protocol as they related to the operation of the physiotherapy room".
It also disputes Bouchard's claim that the physiotherapy room was dark, insisting that even with the main lights turned off, "twilight lighting" remains on at the Flushing Meadows venue.
The USTA add that any suggestion that Bouchard would have won titles in Tokyo - a tournament from which she withdrew - and Beijing - where she retired from her first-round match when trailing Andrea Petkovic - had she not suffered her fall were "entirely speculative and uncertain".
It also claims that Bouchard left the New York venue without taking up offers of medical help after her fall.
Bouchard's lawyer Benedict Morelli told the New York Times in October that they could be seeking damages worth "millions and millions".
The case is now set to be heard by a jury.