John Tomic, the father of Australian tennis player Bernard, has pleaded not guilty to a charge of causing bodily harm in Madrid where he allegedly broke the nose of his son's practice partner Thomas Drouet.
Tomic appeared in court to contest the charge and was told he must return to face trial on May 14.
Tomic senior told the court he had acted in self-defence after tangling with Drouet who arrived with a large dressing on his nose and sat around 40 feet from the accused in the courtroom.
The accused, a former taxi driver who now coaches the world No 53, told reporters: "I don't feel guilty, I didn't do anything wrong."
The incident, which the ATP and Tennis Australia are investigating, took place on Madrid's central Paseo de la Castellana Street on Saturday.
It has been reported that there had been tension between the pair for some weeks and it was not the first time they had clashed.
The 20-year-old Bernard suffered a first round defeat in this week's Madrid Masters, losing 6-3 6-2 to the Czech Republic's Radek Stepanek.
A spokesman for the ATP said: "We can only confirm there was an incident and we are gathering information."
Former Davis Cup star Todd Woodbridge, now head of men's tennis with Tennis Australia, said: "I just want to make sure that everyone understands that this is nothing to do with Bernard and his behaviour."
Tennis Australia later released a statement which read: "Obviously media reports regarding an incident in Madrid are very concerning.
"We are working closely with ATP officials who are investigating the incident and are unable to comment further until the full facts are known."