The arch-realist in Carlos Queiroz refused to downplay the scale of the task. The Iran coach was never going to try the usual manager trick of talking about it as just another game. Quite the opposite.

“Our match with Argentina will be the most important and biggest in Iran’s history,” Queiroz said of the fixture in Belo Horizonte tomorrow. “We consider it as the greatest challenge before us.”

It also involves the most difficult task in modern football. Iran must stop Lionel Messi, a man who seems revitalised after his goal against Bosnia and Herzegovina. For a side that were so content to keep out a team as average as Nigeria in their opening 0-0 draw, it is a daunting prospect.

They at least have a manager who has succeeded in that task before. Queiroz has previously devised a system to stop Messi. Back in the 2008 Champions League semi-final, Manchester United were charged with keeping out Barcelona and stifling a rising Messi. United managed it by the narrowest of margins, winning 1-0 on aggregate.

The result has become renowned for a brilliant defensive performance. Even if it went against United’s notional attacking traditions, it reflected the cast-iron back line that that side were built on. Speaking a few years ago, Patrice Evra put that all down to Queiroz, who was then assistant manager at United.

“I remember the semi-final against Barcelona away when he was speaking with everybody before the second half,” Evra said. “The team felt very strong at Barcelona and this was because of the work of Carlos Queiroz. Tactically, he brought something very important to Manchester United.

“The secret is just to get close, to not let him have the first touch. If he goes quickly with the ball it is very difficult to stop a player like Messi or Cristiano [Ronaldo]. You need to get in strong and close; not foul but be strong and close. After that you can enjoy your game. But if you let him get with the ball and let him run at you, it’s very difficult.”

Similar instructions certainly paid off against Nigeria in their opening 0-0 draw. The dismal nature of the game stood out in a strikingly attacking World Cup but that in itself is almost testament to Queiroz’s defensive organisation.

He admitted there was little attempt to attack but insisted that approach needed to be looked at from the perspective of a limited side like Iran.

Tomorrow, Iran will face a player of almost unlimited ability — at least when put into the right system. There has been a degree of controversy in Argentina since their own 2-1 win over Bosnia and Herzegovina, as it has emerged Messi was one of a number of players who asked manager Alejandro Sabella to change formation from 5-3-2 to 4-3-3 after an underwhelming first half.

But substitute goalkeeper Mariano Andujar played down the stories. “Messi gave his opinion, which he is entitled to, and you shouldn’t go looking for things that aren’t there,” he said.

Of course, it could get very daunting if Argentina score early. That is one potential reality Queiroz cannot yet afford to consider.