In Lyon tomorrow, a football game with a twist. A Great Satan Selection play the House of Allah XI. Ever seen hundreds of diplomats hold their breath for 90 minutes? Just wait.

When Rasoul Zhadem won a wrestling gold medal in the Atlanta Olympics, Iran's president at the time, Ali Akbar Rafsanjani, noted graciously that the victory had "raised Iran's flag in the House of Satan".

There are signs - measurable only with finely calibrated instruments - that relations have warmed since, but darker images still have their resonance. US flags burning, great swelling seas of people chanting and seething, American hostages, 66 of them, blindfolded and fearful and taken away from the world for 444 days.

It is 19 years since the US and Iran last had diplomatic relations, since the pot of Islamic revolution spilled over into the US embassy in Tehran. Tomorrow they come out of the trenches and play a football match in a French field.

A little tinkering by fate has decreed, incidentally, that the match will be played on what was designated by FIFA before the draw as Fair Play Day. "I can tell you that I think there will be something special on the pitch before the match that day," said the man from FIFA.

Certainly a special clash of cultures. The US, sunned from their camp in California, buzzed with the awe of World Cup play and all but indifferent to the fervour their mere presence will create. The Iranians, talking about glorious victory or dying standing up.

The Iranians will play for Allah first, to avoid national humiliation second, for World Cup points third. The small initials IR (Islamic Republic) stitched onto their white jerseys are the key to the passion play. Tomorrow in Lyon will be about more than football.

Every World Cup throws up fixtures which prickle the skin with their nationalistic undertones. Few, though, carry the head-throbbing tensions this game suggests. Only this week the White House was treading cautiously when it responded tentatively and positively to prime minister Mohammad Khotami's declaration some time back that Iran condemned international terrorism. Too enthusiastic an endorsement of Iran's position could have had calamitous consequences in Tehran.

"We'll be treating it as another World Cup soccer game," says Steve Sampson, the preppy American coach, of tomorrow's business. On Thursday the Iranian coach, Jalal Talebi, also refused to be drawn into the political mine field. "If you have political questions I am the wrong man, ask the politicians about those things," Talebi told reporters. "I want to talk about football."

Sepp Blatter, FIFA's voluble new prince, spoke earlier this week about the possibility of the game representing another flash point in the World Cup's calendar.

"We have had more or less anonymous letters saying that groups of Iranian exiles want to disturb the match," said Herr Blatter. The Mujahadeen's public relations department had to go to the trouble of releasing a statement denying that they were intending any disruption.

In a further complication, the Mujahadeen accused the Tehran government of forging threatening letters to create problems for exiled political opponents. "These letters were completely fabricated by the mullahs' information ministry and have nothing to do with Iranians living abroad," said a spokesman. The Mujahadeen had written to FIFA to explain this.

On the field, the hope that sport might help with some rapprochement is keenly held by the Americans in particular. The Iranians are less sure, and striker Khodadad Azizi was quoted in Time magazine this week as saying: "America has mistreated our country. In the war they supported our enemies, Iraq. That's why a victory against the USA will be a special victory."

Soccer people in Iran felt the impact of the long and bloody war with Iraq quite keenly. The team had gone to the 1978 World Cup and, despite scoring just one goal, the national side were expected to build from there.

When war with Iraq broke out the high profile footballers in the country were expected to join the first ranks of Iranian martyrs as an inspirational example to the people. A generation was wiped out.

Both sides have said they will participate in FIFA's fair play rituals, the shaking of the hand of every player on the opposing team. In some circumstances it's a quaint, perhaps trite little exercise. Tomorrow it will have a huge impact on the millions watching at home in Iran. Football will have fractionally adjusted the kilter of the world.

Some American players have expressed the hope that they will be able to publicly swap jerseys at the end of the game, sending a message of humanisation to the people watching in Iran. It would be a curious piece of symbolism: the Yanks handing over their shirts emblazoned with Nike logos and taking receipt of their opponents garments highlighted by the letters IR stitched onto the chest.

Even if they come away with three points and some Nike jerseys, the Iranian visit to the World Cup has not been all happy camping. Having lost another manager midway through last month, they were healing those scars when their tissue-thin sensitivities were upset by French television's decision to broadcast the movie Not Without My Daughter early this week.

The Iranians might have chosen to take the sheer melodramatic awfulness of Not Without My Daughter as a sign of the intellectual degeneracy of the Great Satan. Instead they took umbrage at Sally Field's trenchant, cutting edge radical performance, and by late in the week there was speculation that the Iranians might pull out of the World Cup altogether.

Three players, Mohammad Khakpour, Khodadad Azizi and Alireza Mansourian, attacked the broadcast. Khakpour, the team captain, was quoted by the official Iranian news agency IRNA as inviting reporters to Iran to see for themselves whether the film was a fair portrayal. Mansourian said that Iran's ancient civilisation and culture had been insulted.

"While France says it is the upholder of the banner of human rights, it has weakened the morale of the Iranian soccer players by screening the film," he noted, rubbing French noses in the liberte, fraternite stuff.

A spokesman for the French foreign ministry immediately returned fire, taking a bead on Iran's state-run media. "In France, the media is independent and the government cannot intervene in an independent station's programming."

The Iranians will be nonplussed. They have a passion for their football which borders on fundamentalism. Not to be over simplistic, but soccer is also a tool for progress in some respects. Small steps.

The team, which goes to pray four times a day, had a collective apoplectic fit last week when an Irish journalist, a woman, showed up to watch them train. But things are changing slowly.

Qualification was declared a victory of faith rather than of football, and it is that belief in the divine tactician which has created such an earthly revolving door for Iranian managers. There have been four of them in the past seven months.

There might be something to the faith aspect, though. Iran were the last team to qualify for the World Cup finals. They staggered across the finish line. Having beaten China 4-1 last October 17th, Iran went on to: lose to Saudi Arabia, draw with Kuwait, lose to Qatar, lose to Japan, draw with Australia, draw with Australia. And they still qualified. Allah be praised.

When the team returned from the historic qualification in Australia which had been watched by six million viewers at home, Tehran got dizzy with excitement and for the first time ever a women's seating area had to be set up in the Azadi Stadium to cater for the huge numbers turning out to see their team's homecoming.

The result was a move to make the women's seating areas a permanent fixture in stadia in the country. One small step then.

Another one tomorrow, perhaps.