Bernard Tomic has been criticised over his use of the word "retard" during a Wimbledon press conference.
The 23-year-old was responding to a question about being made to wait on court for his opponent, Spaniard Fernando Verdasco.
Learning disability charity Mencap has now called for the world No.19 to apologise.
In a post-match conference, he was asked: "Tennis etiquette requires that both players arrive on court at the same time. You were kept waiting about eight minutes. Any idea why?"
Tomic replied: "Yeah, I did get to the court prior to him very early, and unfortunately I had to stand on court like a retard."