Bernard Tomic's father and coach John is due to appear in a Madrid court later on Monday after he attacked one of his son's coaching team on a street in the Spanish capital at the weekend, local police sources said.
Media reports said the man Tomic assaulted was Bernard's practice partner Thomas Drouet, although police could only confirm the victim as "the son's coach".
The incident, which the Association of Tennis Professionals (ATP) and Tennis Australia (TA) are investigating, took place on the central Paseo de la Castellana street on Saturday and Tomic's father was later taken into custody at his hotel, police said.
He had been released and was due to appear in court at 2 p.m. local time (1200 GMT) on Monday to face a charge of causing bodily harm with reports claiming the victim suffered a broken nose.
John Tomic called Australian sportswriter Linda Pearce early on Monday but would not elaborate on the incident, saying: "I just want to say that I'm not in the jail, how they are writing.
"Hard to explain to you... I'm not in the jail, just say like that. Tomorrow I will say."
A spokesman for the ATP on site in Madrid said on Monday: "We can only confirm there was an incident and we are gathering information."
TA official Todd Woodbridge, a former Australian Davis Cup player, said there was little he could add but confirmed that, to his knowledge, an incident had taken place.
"What's important for us at Tennis Australia is that this allegation is thrown toward John, his dad, and not to Bernard," Woodbridge, TA's head of men's tennis, told 3AW radio.
"I just want to make sure that everyone understands that this is nothing to do with Bernard and his behaviour."
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."
Tomic, who lost 6-3, 6-2 in the first round of the Madrid claycourt 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.
Photograph: Clive Brunskill/Getty Images