Australia soccer coach Pim Verbeek admitted his side was outclassed by Germany after a 4-0 loss at the World Cup on Sunday.

Germany now sit atop of Group D, followed by Ghana, who beat Serbia 1-0 in Pretoria earlier on Sunday, both on three points while Australia lie at the bottom of the group due to inferior goal difference.

"It was not an easy game for us. Germany was better," Verbeek told Australian Associated Press (AAP).

"We all knew they were a candidate for this World Cup because they have a fantastic team. We have to learn from this game, and we have six days to recover physically and mentally," he said.

The Australian team also had to pay a heavy price for the dismissal of Tim Cahill, receiving a straight red card in the 56th minute by Mexican referee Marco Rodriguez for a very clumsy challenge on Bastian Schweinsteiger.

Cahill will miss the Ghana match because of an automatic one-match ban for his send-off.

Germany's coach Joachim Low said he was pleased with his side's clinical performance, though he felt there was still room for improvement.

Tens of thousands of Australians and visitors have been packed in city of Sydney, where large video screens brought the World Cup game live from South Africa.

Australia will face Ghana on June 19 in Rustenberg, South Africa for their second group match.