Arsenal mentor Arsene Wenger says "tough cookies" Australia will be giving three-time champions Germany sleepless nights before their World Cup opener.

Wenger gave the apparently outclassed Socceroos a 40 per cent chance of shocking Germany on Sunday, a result which would throw Group D wide open.

"If I was the national team coach of Germany and I had to play Australia, I wouldn't sleep well," Wenger told Channel Nine.

"Let's say for me it will be 60 (per cent chance for) Germany, 40 Australia.

"I give them a chance against Germany but we'll see.

"It will be very interesting."

Australia beat the odds to reach the last 16 of the 2006 World Cup before being controversially ousted by eventual winners Italy.

They are currently ranked 20th in the world to Germany's sixth.

"Usually they are very tough cookies in the World Cup, Australia," Wenger said.

"Sometimes Germany are slow starters in the big competitions, maybe Australia can take advantage of that because it will make it a very interesting group."

Australia will also face Ghana and Serbia in Group D.

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