Socceroo fans are ready again to don the green and gold and brave the winter cold, despite a crushing defeat by Germany in the first round of the World Cup.

More than 20,000 fans from Sydney and other parts of the world packed Cockle Bay and Tumbalong Park in Darling Harbour on Monday to watch the first-round match televised live from South Africa at 4.30am (AEST).

Germany struck early, scoring two goals in the first half, then sealing victory with two more in the second half, with Australia's woes made worse when Tim Cahill was sent off for a late tackle.

The 4-0 victory added frost to a winter low of 6.9 degrees recorded by the weather bureau in Sydney's CBD.

Fans Brendon Heape and Nausicaa Joannes arrived at 11.30pm (AEST) on Sunday. "I can't feel my feet. I'm so cold," Ms Joannes said.

Sydney is one of only six international sites to host live broadcasts of all 64 games of the World Cup, shown on four giant screens at Darling Harbour.

A capacity crowd of 12,425 packed the Cockle Bay venue and adjacent Tumbalong Park reached its maximum of 7,604 people, a NSW Transport spokeswoman said in a statement.

Thousands more were stacked along the barricades trying to get a glimpse, while others packed Darling Harbour's pubs and clubs that remained open until the match ended.

Northern beaches residents Meaghan Phillips and Brendan Ashcroft arrived at 7.30pm (AEST) on Sunday but were a bit dismayed when Germany scored its third goal and fans began departing the area.

"I understand, it's hard to see your team lose like this," Ms Phillips said.

The couple vowed to come out again and cheer on the Socceroos but with a few more layers of clothing to fend off the chill.

Diehard fans Rasha Sleybey and Tamar Karkour arrived at 2am (AEST) on Monday from Fairfield, in Sydney's southwest.

The A-league football fanatics wore green and gold frizzy wigs but said Monday's defeat was hard to stomach.

"Could it get any worse?" Ms Sleybey said near the end of the match.

"I'm just waiting for us to score our own goal.

"Why don't we just kick it back into our own net?"

Ms Karkour said the loss was "a bit disappointing" but the pair vowed to brave the conditions for Sunday's match against Ghana.

"I just think everyone has to group together and see how we go," she said.

Football crazed fans from all over the globe chanted and cheered in Sydney's pre-dawn cold.

Smiles abounded but it was the German nationals who celebrated long after official time expired.

Jana Bouhme, from Hamburg, was with a group of 10 countrymen.

She criticised the Australian fans' lack of musical support for their team.

"You don't sing," Ms Bouhme said.

"We have so many different songs we can sing.

"I think that's the reason we win all the time, because we have a lot of fans that sing."

Police made only one arrest - a man who ignited a flare was issued a fine of $1,000 and escorted from the area.

"They were all well-behaved," a police spokeswoman told AAP.

"Only one nut out of all those people."

Australia squares off next against Ghana on Saturday at 4pm South African time (0000 Sunday AEST).

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