With World Cup fever gripping Australia, about 5,000 fans including Brazilians, Croatians and Koreans as well as Australians gathered in Sydney by 1 a.m. (1500 GMT Tuesday) to watch matches on a huge screen near the city's harbour.

Police said an unidentified 25-year-old South Korean fan climbed up a road sign amid wild celebrations after watching his team fight back to win their opening finals match 2-1 over Togo.

They said the man fell heavily to the pavement and collapsed against a wall as he tried to get to his feet.

He was given emergency treatment at the scene before he was taken to hospital, where he remains on life support, police said.

"While we appreciate the fans' desire to celebrate and have a good time, we would encourage them to do so safely," police inspector Chris Keen said in a statement.

Australia erupted into nationwide celebrations early on Tuesday after their national team the Socceroos came from behind to beat Japan 3-1 for their first win in a World Cup finals match.