Melbourne:Ethnic violence again marred the Australian Open on Friday when rival Serbian and Bosnian fans hurled chairs and missiles at each other, sparking condemnation from players and police.
Some 30 people in their late teens and early 20s were evicted after the clashes, which left one woman injured, following Serbian Novak Djokovic's win over Bosnian-born American Amer Delic, police said.
Disturbances continued outside Melbourne Park after the men and women were thrown out, with taunts and punches thrown.
In unprecedented scenes, the two sets of supporters gathered at Garden Square outside Rod Laver Arena after the match with the riot sparked by verbal abuse.
Dozens of chairs were then hurled by the groups shouting "C'mon" as passers-by cowered before police and security guards stepped in.
One woman was hit on the head by a chair and needed treatment for cuts and bruises. Two people were charged with riotous behaviour and discharging a missile.
"A number of people got into a chair-throwing contest between two groups with the result that 30-odd people were ejected from Rod Laver," said Inspector Chris Duthie of Melbourne East Police.
"We're charging two on summons and one will be receiving an on-the-spot fine.
"The matter was dealt with very quickly and very effectively by the police and we expect no more problems at this stage."
Asked what the dispute was about, he replied: "I don't know, probably ethnic rivalries."
The Australian Open has gained an unsavoury reputation for ethnic clashes.
In 2007, the tournament was overshadowed when Serbian and Croatian fans, wearing the national colors of the bitter Balkan rivals, attacked each other with flagpoles, bottles and boots.
Then last year, police used pepper spray to subdue rowdy elements of the crowd watching a match between Konstantinos Economidis of Greece and Chile's Fernando Gonzales.
In response, police numbers were boosted this year and officers were issued with containers of capsicum foam to target troublemakers, although these were not used on Friday.
Delic had appealed before the match for both sets of fans to behave.
"I'm really sad to hear about it. As I said a couple days ago, there's absolutely no place for that here. This is a tennis match," he said.
"I don't know who started, who finished, or whatever. Either way, on both sides I'm sure there were guys that wanted to cause problems. It's like that everywhere in the world.
"Unfortunately, it happened here today. I'm sure some innocent people might have gotten injured. It's sad. I don't know what else I can say."
Djokovic was reluctant to get involved, saying only that players had no control over what fans did.
"I am happy when I see that I have my own group of fans that are supporting me in a fair way, of course, not provoking my opponent and everything is going in a sportsmanship way," he said.
"I didn't know about this encounter whatever they had outside of the courts."
Despite warnings that clashes could happen, Inspector Duthie defended police actions.
"We have a a very effective police unit here at the moment," he said.
"You can't stop everything happening but again we will make sure this sort of behaviour doesn't happen again. We have plans in place to make sure this doesn't happen and it was dealt with very effectively and very quickly."