Who fights outside of a tennis match?

A couple of days ago, I referred to John McEnroe as being the first player to ever be ejected from the Australian Open. Well yesterday, there was a match between Novak Djokovic (a serb) and Amer Delic (a bosnian-born US player). Now I know there's a history between this 2 countries (read: Slobodan Milosevic), but you wouldn't expect anything to erupt at a tennis match right? Well, it's safe to say that nothing actually did happen during the match. The players were cordial throughout, as they are friends. However, outside of the stadium, Serbian and Bosnian youths got into a fight. Just watch the video as these kids start tossing chairs at each other. Apparently, some girl got drilled on the head. It's understandable that an event like this would happen at a soccer (futbol) event or, as a stretch, even a basketball game. But tennis? Are you fuckin kidding me? I didn't even think that that many Serbs and Bosnians would travel to Australia to begin with. What's next? Golf? Badminton? Gymnastics? Chess?

Unbelievable.