The father of Imanol Harinordoquy brought the Top 14 Basque derby between Biarritz and Bayonne to a halt by running onto the pitch to defend his son.
According to AFP, France international Harinordoquy's father came down from the stands in the sixth minute of the Tuesday night clash and faced up to Bayonne flanker Jean-Jo Marmouyet after his son got involved in a punch-up far from the action.
Harinordoquy senior's admirable sense of family loyalty was brought to an abrupt halt by Bayonne fly-half Benjamin Boyet, who tackled him to the ground before Biarritz hooker Benoit August stepped in to restore order.
Christian Gajan, Bayonne's director of rugby, was outraged by Harinordoquy's father's behaviour.
"I find his behaviour deplorable that he came onto the pitch to defend his son by boxing with (Jean-Jo) Marmouyet at the beginning of the match," he said.
"You could have been mistaken for believing it was a youth match between two local villages, it was a scandalous episode."
Harinordoquy junior - who is known as one of the tougher customers in the sport and a veteran of three World Cups - preferred not to comment.
Biarritz won the 100th Basque derby with the last kick of the game on Tuesday as Julien Peyrelongue landed a penalty to make the score 21-19 and give the hosts only their second win in 11 matches.
Three players were sin-binned during the match.