Police ejected about 150 spectators from the Australian Open today after an ugly brawl broke out between Serbian and Croatian fans inside the ground.
Fans wearing the national colours of the bitter Balkan rivals clashed in the Rod Laver Arena after taunting and hurling insults at each other.
Witnesses said they kicked and punched each other and set upon their rivals with flagpoles before dozens of police and security staff rushed in to end the melee and eject the combatants after confiscating their tickets.
"They were mostly Serbians ejected as they were upsetting the Croatians," Victoria state police spokeswoman Katherine Jess said.
Earlier, a group of fans gathered in central Melbourne and lit flares as they made their way to the stadium.
"It's bad because you go to the tennis and you go to watch and then it ends up in an actual brawl, it's just ridiculous," a Croatian fan called Marina told Australian Associated Press.
"You go to cheer on your actual player, not to go and fight."
Tennis Australia chief executive Steve Wood said there were no injuries or arrests and security staff had acted swiftly to end the fight.
He said fans in national colours had always been a welcome feature of the season-opening Grand Slam but organisers would not let troublemakers ruin the day for other patrons.