Tennis Australia have confirmed Bernard Tomic's father John has been involved in an incident with his son's training partner in Spain.
Tomic senior, who is his coach, has reportedly been arrested for allegedly striking Frenchman Thomas Drouet and is believed to be facing court in Madrid.
Drouet is understood to have been knocked out and suffered a broken nose following a head-butt by Tomic.
The tennis journalist Matt Cronin said that he understood Drouet stepped in when Tomic tried to assault his son.
Meanwhile, Bernard Tomic continued his poor start to the European clay court season as he lost 6-3 6-2 to Czech veteran Radek Stepanek in the first round of the Madrid Masters.