Graham Arnold believes his Australia side can deliver this World Cup's latest upset win when they face Lionel Messi's Argentina on Saturday.

There have been no shortage of shocks at this tournament, with the Socceroos' Group D defeat of Euro 2020 semi-finalists Denmark among them.

That victory set up a last-16 tie against Argentina, who were themselves on the wrong end of a surprise result when they lost their opening game to Saudi Arabia.

Australia have enjoyed some success against La Albiceleste in the past, too. Coach Arnold was part of the only senior Socceroos team to beat Argentina back in 1988, although their Olympic team added another triumph last July.

"I just think Argentina bring the best out of Australia," said Arnold on the eve of this latest meeting.

"Our performances every time against Argentina have been very strong and very good, and we go into the game with a lot of belief and a lot of energy. We focus on ourselves and our job."

Harry Souttar was perhaps Australia's standout performer of the group stage and added: "We've already surprised a few people with the results we've had, so we're looking to go and surprise a few more."

Indeed, surprises are perhaps even more likely now in the knockout stage, as Arnold suggested.

"The group games are past us now. It's a whole new ball game," he said. "It's a one-off game, and anything can happen in one-off games.

"There's no disrespect to Argentina at all, but it's 11-v-11, it's 10 blue shirts against 10 yellow shirts, and it's a battle, it's a war. We've got to fight that."

Regardless, Australia remain very much the "underdogs", but that tag suits Arnold, who dismissed the suggestion of any fatigue setting in.

"Everyone's an underdog until you have success," he said. "Nearly everyone in the world at some stage in their life has been an underdog. It's until you have success that you're seen as [that].

"Australia's the underdogs and we love that. We love having our backs to the walls and nobody giving us a chance and going out and fighting the Aussie spirit way. That's our strength."