John Tomic, a burly former taxi driver who now coaches his son, and the man he tangled with, Bernard's practice partner Thomas Drouet, both turned up for the hearing in the centre of the Spanish capital.
Drouet had a large dressing fixed to his nose with white surgical tape and a neck support, while Tomic appeared unscathed apart from a small cut above his right eye and the pair sat about 15 metres apart outside the courtroom.
After consultation with the judge, it was decided that because Tomic disputed the charge of causing bodily harm the hearing could not take place and a further court appearance for the pair was scheduled for May 14, court officials said.
"I don't feel guilty, I didn't do anything wrong," a weary-looking Tomic, whose light blue shirt had sweat circles under the armpits, told reporters.
He declined to comment further and left the court by a side entrance to avoid the reporters and television cameras waiting in the street.
The incident, which the Association of Tennis Professionals (ATP) and Tennis Australia (TA) are investigating, took place on Madrid's central Paseo de la Castellana street on Saturday and Tomic was later taken into custody at his hotel, police said.
He was ordered to appear in court and could be handed a prison sentence of up to three years and a possible fine if found guilty.
A subdued Drouet, who will return to his home in France before coming back for the May 14 hearing, was reluctant to discuss the details of the incident as he left the court.
He said he would consider maintaining his working relationship with Bernard Tomic as long as the father was not on the team.
Australia's Herald Sun newspaper quoted Drouet as saying that Tomic had treated him like a "dog" for years and that he had punched his son in the mouth at a training session last week, leaving him in tears.
Shortly before the head-butting incident, John Tomic had told him he was sacked and would not be getting paid.
"I thought he was going to say sorry for the verbal abuse, but no," Drouet told the paper. "He spat in my face, then walked away, and said he wouldn't pay me any more.
"I said, 'OK, John, you are a real man. That's fine. Bernard will pay me'. And he head-butted me."
Tomic's Spanish lawyer, Carmen Dieguez, told reporters that while Tomic did not dispute that he had caused Drouet's injuries he had had no other choice to butt him as Drouet had grabbed him by the arms.
Tension between the pair had been rising for some weeks and it was not the first time they had clashed, she added.
Ukrainian player Alexandr Dolgopolov said he and his father found Drouet lying on the ground after the incident, which they did not witness.
"We discovered him on the pavement and we tried to help him. He was really not well," Dolgopolov told Reuters after his first-round defeat by Dutchman Robin Haase at the Madrid Masters on Monday.
"He was struggling to stay conscious. We gave him some water while waiting for the ambulance.
"We (players at the Madrid Masters) speak a lot about it. We did not see anything but we can guess."
Reacting to initial reports about the incident, tennis Australia official Todd Woodbridge, a former Australian Davis Cup player, said: "What's important for us at Tennis Australia is that this allegation is thrown toward John, his dad, and not to Bernard.
"I just want to make sure that everyone understands that this is nothing to do with Bernard and his behaviour," Woodbridge, TA's head of men's tennis, told 3AW radio.
TA later released a statement.
"Obviously media reports regarding an incident in Madrid are very concerning," it read.
"We are working closely with ATP officials who are investigating the incident and are unable to comment further until the full facts are known."
Asked if he was worried about being thrown off the Tour, John Tomic said: "No I just said I didn't do anything wrong."
Tomic, who lost 6-3 6-2 in the first round of the Madrid clay court tournament to Czech Radek Stepanek on Sunday, has long been the great young hope of Australian men's tennis but a lack of consistency over the season has kept his world ranking relatively low despite strong showings in grand slam events.
He has also enjoyed his fair share of controversy in his short career, frequently clashing with Australian tennis officialdom.
One of the earliest clashes came when his father, who also acts as his coach, ordered the then 16-year-old to walk off court at a development event in protest at inaction against what he alleged was repeated foot-faulting by his opponent.
During a late-season slump last year, a string of Australian tennis coaches suggested Tomic dump his father as coach and work with someone new.