Nigeria manager Stephen Keshi believes opposite number Carlos Queiroz is Iran's biggest threat at the World Cup.

The sides meet in Curitiba on Monday and, with Argentina and Bosnia-Herzegovina also awaiting in Group F, it is a game which could provide the best chance for either side to take three points.

Iran came into the tournament as perhaps the least fancied of all 32 nations but in Quieroz they have a well travelled campaigner at the helm.

He has managed his native Portugal, as well as South Africa and the United Arab Emirates at international level, had a brief tenure at Real Madrid and spent several years as Sir Alex Ferguson's assistant at Manchester United.

Keshi admits to having a limited knowledge of the Iranian side but takes the challenge of besting Queiroz seriously.

"I think an experienced coach is their biggest weapon, because he is well experienced, he knows the game well," Keshi told FIFA.com.

"They have a very good coach and I'm sure they also have some quality players. We don't know Iran very well, but we'll see them on Monday.

"For the Iran game we have to be focused. We have to concentrate and do our job. We're not going to take Iran lightly because they're not going to take us lightly. So we have to go out with everything that we have."

As for his own side, Keshi is relying on an experienced spine to steer an otherwise youthful group.

"This squad is probably a year-plus old, it's a new team," he said. "Most of the players are young. We're still in the process of getting

"In two years' time we can be much better. I pray that Vincent Enyeama, [Joseph] Yobo and [John] Obi Mikel will bring all their experience. Youth is good, but if we can combine youth and experience that will be great for us."

Queiroz knows Iran are up against it on the biggest stage of all, but has a simple game plan to maximise their chances.

He has called for focus, enjoyment and a refusal to admit defeat.

"The most important is the first game," he said.

"We cannot miss this opportunity to face them with pleasure and enjoyment. We must treat them as they are, no more, no less. There are no perfect teams in the world.

"Our goal is simple: if they make a mistake, we will be ready to capitalise. We have to be in the right places at the right time.

"Not 90 per cent (of the time), but 100 per cent."