"The game against Croatia showed that they are vulnerable in places," Viduka told reporters at team training.

"I thought Croatia should have got something out of that game, I thought they were the better team."

Viduka was asked if Australia could exploit the Brazilian defence out wide as Croatia did down the flanks.

"I don't know what to expect on Sunday, but they are not superheroes or anything like that, they're people like us and why not?" he said.

Viduka said it was a concern that Australia gave away four yellow cards in their exhilarating 3-1 win over Japan last Sunday.

"That's a bit of a concern for us, because a few of them were given out quite lightly, but we have to keep every man available for every game and we'll see how (coach) Guus Hiddink is going to re-arrange the team," he said.

Viduka said every game at the World Cup was a crunch one for the Australians, making their first finals' appearance in 32 years.

"You saw in the Japan game it was end-to-end stuff, in these games it's not like a league or anything, you have to go for it and that means you could vulnerable as well. I think we have to go for it (against Brazil)."

Viduka said the manner of Australia's win over Japan, with their three goals coming inside the last eight minutes in energy-sapping heat in Kaiserslautern, had given his team a massive lift in confidence.

"To get the three points in the first game against Japan and in the manner that we did do it gave everybody a big high afterwards," he said.