The equation from a French perspective looks very simple. The France team plus Zinedine Zidane, Lilian Thuram and Claude Makelele, minus inexperience, disharmony and crisis of confidence, equals World Cup qualification. Voilà
They travel to Dublin still giddy with the exhilaration that greeted Zidane's pledge to don his blue halo once more. Before the second coming, Lansdowne Road was feared as the rock upon which France's World Cup hopes could founder. Now, nobody will countenance the possibility that Zizou might not be able to save the day. Even his team-mates are in awe. Thierry Henry has evidently seen the light: 'What I am going to say may sound over the top, but it's the truth. God exists and he has returned to the France team.'
It is as well that Brian Kerr cares little for the aura around French football. He is no fan of his adversary Raymond Domenech (then again, nor were most of the French coach's own players before Zidane and company returned). He is not overly impressed with the French for dealing themselves a new hand just as Group 4 is cranking towards the moment of truth.
You can see Kerr's point. The France squad are transformed from the discordant depressives Ireland tussled with in Paris a year ago. The team were burdened, the coach had lost the plot, the fans were edgy - it spoke volumes that the noisiest voices during the Marseillaise were wearing green, didn't know the words and crooned along for a giggle. French morale stank.
The list of players who were not available in Paris but who are raring to go on Wednesday is ominously strong: Zidane (Real Madrid), Thuram (Juventus), Makelele (Chelsea), Patrick Vieira (Juventus), Willy Sagnol (Bayern Munich), Ludovic Giuly (Barcelona). Lucky, lucky Domenech.
It is difficult to overstate the impact Zidane's change of heart has had on his team. France's sporting icon was coaxed back into the international arena by the same gut impulse that triggered Roy Keane. Both came to miss the taste of football on the greatest stage, matches on the highest plane. Neither has enjoyed enough of those moments in the past couple of years at his club.
But the critical difference between these momentous U-turns is that while Keane returned to give his all, Zidane came back only on the condition that two powerful friends came with him. France are recharged from back to front: Thuram can boss the defence, Makelele protect midfield and Zidane conduct the attack.
Goalkeeper Gregory Coupet explains the radical difference permeating the team: 'Without them last year we were in trouble. You could see in some players' eyes they didn't know who to pass to.' As Djibril Cisse adds: 'We all feel better to have these players back. We have more confidence, more serenity and, above all, more quality in the team.'
Kerr prefers not to believe the hype. It is worth recalling that France were poor at Euro 2004, and all three of the returning anciens were in the meek XI who were turfed out by Greece. Tactically and psychologically, even the heavy hitters struggled not so long ago.
'At the time of the draw, people's minds were clearly jizzed up by the idea of having the previous world champions and European champions in the group. But the pressure is on them,' says Kerr. 'Of course they have had to live with the disappointment that they haven't been able to score a lot of goals or win a lot of games. Now they have brought in the heavies and the expectancy is that they are going to run all over us, all over the last four games.' Expectancy has never won a football match, though.
The group of draws has been waiting for someone to make their move and although all eyes are on France, Ireland are summoning the spirit of Holland 2001 for inspiration of their own. Back then, in another tense qualification crusade, the Dutch were felled at Lansdowne by one Jason McAteer goal, 10 men in green defending as if their lives depended on it and the infinite power of a rousing, partisan audience.
Same again, Brian? 'We want all those factors in place for us to do it when we're playing one of the world's greatest teams. The public have a part to play. It's not about coming and being an interested onlooker. You should be coming to the game the way I saw it in Albania, where there was general hostility towards us - in the nicest possible way. It wasn't an aggressive hostility, but it was hostility towards the referee's decisions and anything that was going to stand in the way of their team doing well. That's the way it should be.'
Notably, Ireland have beaten only one team - Saudi Arabia - in the top 50 of Fifa's world rankings in a competitive fixture since Holland 2001. Ireland's reputation as being hard to beat lives on, but finishing teams off is a serious problem. In particular, throwing away the lead twice against Israel was avoidable, annoying and expensive. Imagine what a difference four more points at this stage of the game would have made.
The early draws in Switzerland and France boded well, but the onus on beating both at home now is immense. Would Kerr take another draw against the French? 'I'd take anything,' he says. 'We don't know what results we are going to need. We are unbeaten in the group after seven games, with three games to go. But to be unbeaten in the last three games, we might have to win some of them.'
There is an undercurrent of a grudge to settle. Kerr was critical of the French response to their last meeting, when Ireland played with excellent tempo and passing. 'I felt Domenech was very dismissive and denigrating of our team and our approach. I didn't think there was due respect for our performance by their staff. I didn't feel it was nice.'
As if there were any more reason to go for the jugular at Lansdowne Road.
