Once they were the best of friends, indeed a decade ago the older man used the help of the younger one to gain power, then promoted his protégé as his potential successor. But now such are the developing battle lines that the two could be in football's equivalent of an OK Corral-style shoot-out to decide who becomes the game's most powerful man.
The two are Sepp Blatter, president of Fifa and Michel Platini, president of Uefa, both of whom could contest the right to run the sport when Blatter's terms ends in 2015. Part of the reason for the fallout is 77-year-old Blatter, like many in power, does not know when to surrender the reins. Although when re-elected in 2011, he promised this would be his last term, he said last year: "There may be circumstances that I'm still there and nobody will take on Fifa, I don't know."
Since then more signs have emerged suggesting he feels nobody has emerged and he wants to go on and on. Those close to Platini also resent the way Blatter has built up an imperial presidency with Fifa resembling the court of Louis XV. The leader is always in the limelight making extraordinary statements that cause enormous problems.
This week's row over the 2022 Qatar World Cup illustrated this dramatically. In an interview last year Blatter categorically stated: "It is not possible to have the Qatar World Cup in the winter. The problem of the World Cup 2022 is that there was a bidding process and they had a bidding paper where it said, the World Cup 2022 has to be played in June/July. So, if something is to be changed, first of all, the Qataris must ask us to change it. They have never asked. They have never had any discussion with us. If they ask, then maybe something would happen."
Then two months ago, despite no such request from Qatar, Blatter suddenly announced that the Fifa executive meeting in October would decide to move it to winter. It appeared that he was persuaded by medical advice that a summer World Cup in the Qatar heat was impossible for players and fans.
Blatter's U-turn came as a complete surprise to Platini who said: "I did not know Mr Blatter wanted to change. He was going on his holidays. When Mr Blatter speaks to the press, he doesn't ask me."
For Platini this outburst was clearly another example of Blatter making dramatic announcements without consulting Fifa's executive, of which Platini is a member.
The result was the shambles in Zurich this week where, like the Duke of York having marched his men up the hill, Blatter announced that no formal decision on 2022 would be taken until a special taskforce reports back.
Platini, who has revealed he voted for Qatar, has made no secret of his desire for a winter World Cup. However, unlike Blatter, he sees arriving at a decision about a winter World Cup as a gradual process much in the way Financial Fair Play, to make European clubs live within their means, is being introduced. Platini is immensely proud of how this attempt to cure what he calls "financial doping" is now widely accepted in Europe, even by the once-sceptical Premier League.
The Frenchman is well aware that a winter World Cup will be disruptive and the European Leagues and the Champions League need to be protected. He wants to take the World Cup to different locations around the world and is opposed to any attempts to characterise opponents of Qatar as Eurocentric.
Platini is yet to announce whether he will take on his old mentor for the Fifa presidency. However, those close to him are preparing the ground. They will argue that Uefa's member associations receive more money than those reliant on Fifa. They have also begun to sketch out how Platini will run Fifa. As one of his closest advisers said, Platini will make Fifa a more "normal" organisation where the president is the first among equals, not a monarch.
If he does run, it will be as the champion of Europe protecting the continent's football from an assault by a Blatter-led Fifa.