No scope for slip ups for Messi and Co

Argentina are hot favourites to beat Australia on Saturday in pursuit of Lionel Messi's dream of winning a first World Cup, but they more than anyone have learned not to underestimate an underdog, especially the hard-battling Socceroos.

Argentina suffered one of the biggest upsets in World Cup history with their opening defeat to Saudi Arabia, but recovered their poise to swagger past Mexico and Poland into the last 16.

It was a dramatic turnaround for one of the pre-tournament favourites following the doom and gloom that met their opening result.

"I think we're back to being the team we used to be" before the Saudi loss, said goalscorer Alexis Mac Allister following Wednesday's 2-0 win over Poland.

Argentina came into the World Cup on a 36-match winning run and on the brink of equalling the unbeaten world record.

But after a fast start against the Saudis in which Messi gave them a 10th minute lead from the penalty spot, their fortunes quickly unravelled.

Suddenly, Argentina were facing the very real prospect of crashing out in the group stages.

And even though they won their next two matches 2-0 against Mexico and Poland, it was not always convincing.

Argentina coach Lionel Scaloni, however, vowed that his team would give their all to not be at receiving end of any more upsets.

"We will break our backs on this pitch to compete, we know how difficult this World Cup is, this is football," Scaloni said.

"We saw what happened yesterday (when Germany and Belgium were knocked out in the group stage) but this is not surprising. When you say big national teams deserve to be in the next stage, that doesn't always happen."

Australia, ranked 35 places below Argentina, have already surpassed expectations in winning twice to earn their place at Qatar's Ahmad bin Ali Stadium this weekend for one of the biggest games in their history.

Both teams have only two full days to rest, a factor Argentine manager Lionel Scaloni called "madness".

"We've almost got no time to let it all sink in, enjoy it ... it's recovery, recovery, recovery," concurred Australia's assistant coach Rene Meulensteen.

"But one thing I can tell you, we will be ready."

Overjoyed and exhausted after reaching the World Cup knockout stage for only the second time, Australia will have to play the game of their lives to overcome an Argentina side oozing talent from front to back.

They will be relying on the same fitness, muscle and never-say-die attitude that saw off Tunisia and Denmark, epitomised by hulking defender Harry Souttar, who has played out of his skin despite only just returning from a lengthy layoff.

"They are tough. Anyone who thinks the match against Australia will be easy is wrong," Argentina's Scaloni said.