Lionel Messi and Argentina try to avoid World Cup upset vs Australia

Australia's players speak in glowing, almost reverential terms about Lionel Messi.

"He just does things that, you know, no one else can do," forward Mathew Leckie said.

Milos Degenek went even further. "Probably," the Socceroos defender said, "the best footballer ever to grace the game."

Imagine, then, how they'll be feeling on Saturday when they share the same field as Messi and his Argentina team in the last 16 of the World Cup.

These are pinch-yourself times for a group of unheralded players who were expected to be on their way home by this stage of the tournament. Yet here they are in Doha, looking to cause the latest upset in a World Cup that has been full of them right from the moment Saudi Arabia shocked Argentina in perhaps the most unlikely win in the tournament's 92-year history.

That set the tone for the past two weeks, during which Japan has beaten both Germany and Spain, Morocco has defeated Belgium, Tunisia has beaten France and, let's not forget, Australia has stunned Denmark.

The Australians want to add to that list.

"No one expects us to win," Leckie said. "So let's shock the world."

Don't expect any complacency among the Argentina squad, though. Not after what transpired against Saudi Arabia during the group stage.

"We know, at the moment, everything is very difficult," said Messi, who is bidding to win the World Cup in his fifth and likely last attempt.

"All the opponents are complicated. We know it as well as anyone."

There is a growing feeling, though, that Argentina might have come through the worst of the storm. It is only a week ago that Argentine soccer was going through a period of introspection, digesting one of its most embarrassing results ever.

Then, after an hour of its second group match against Mexico, the Albiceleste were being held 0-0 to raise the genuine prospect of a group-stage exit with a game to spare.

Now, Argentina has qualified as the winner of its group and is facing the world's 38th-ranked nation, which is playing at this stage of the World Cup for only the second time, after 2006. Netherlands or the United States will be the opponent in the quarterfinals.

Midfielder Rodrigo de Paul suggested on Friday that Argentina's surprise loss to Saudi Arabia actually had a positive effect on the team.

"We found ourselves in a situation that we weren't used to. It had been a while since our last defeat," de Paul said of the end of the team's 36-match unbeaten run. That's when you see the character of the team, what kind of group we are. That was the moment to rise."

None of Argentina's players will dare get ahead of themselves but it's undeniable that the draw has opened up for them.

"We went back to being what we were for a long time," Messi said after Argentina's 2-0 win over Poland that secured a place in the last 16, and how we were looking to be at the beginning of the World Cup, which for different reasons we could not manage.

"It gives confidence for what is coming."

Argentina coach Lionel Scaloni looks to have finally found a winning formula in Qatar. The center of midfield now appears to be set, with Alexis Mac Allister and 21-year-old Enzo Fernandez having forced their way into the starting team alongside Rodrigo De Paul.

Up front, Julian Alvarez has dislodged Lautaro Martinez and should keep his place against Australia, fresh from finishing off a 27-pass sequence for an exquisite second goal against Poland.

"We have an idea of how we want to play, but we'll see how the players feel after training today," Scaloni said.

The only place that looks up for grabs is at center back, with Lisandro Martinez having dropped out against Poland perhaps so Argentina had a taller player to deal with the aerial threat of Robert Lewandowski.

Given only one player in Australia's 26-man group plays in Europe's top five leagues, it appears to be a mismatch at Ahmad Bin Ali Stadium.

And then there's the Messi factor, a subplot which is hanging over the World Cup as he looks to win the only major title to elude him in his career.

"I think they're obviously driven by the motivation that it could be Messi's last World Cup," Degenek said, "and he wants to win the World Cup and end it on a high. For us, it's about stopping that. Unfortunately, I'm a big fan of his, but I'd love to win the World Cup probably more than him.