In 13 days time the drug-fuelled suspicion that is the modern Olympic Games will end in Sydney and just 150 seconds of undiluted excellence will begin in the Paris suburb of Longchamp. It will be a classic sporting clash between a champion and the young pretender, between the proven and potential, and it will be conclusive. Or rather we hope it will be conclusive. The Prix de l'Arc de Triomphe has a habit of punishing presumption.

The list of champions who have stumbled to defeat around Longchamp's unique mile and a half is long and impressive. Names such as Sir Ivor, Nijinksy and Troy, legends of the game. But funnily enough the truly great names tend to win it, contemptuous of excuses.

That's why the giant frame of Montjeu has lurked over the Arc all year to such an extent he is now an odds-on favourite. Last season the French champion justified the hopes of those who thought him the real deal and then expanded those hopes. Montjeu was a great Arc winner, more than entitled to look at the former great names like Sea Bird, Mill Reef and Dancing Brave straight in the eye. Except that Montjeu would rather spit in their eyes.

"He has an attitude," says rider Michael Kinane. "But if you were that good, you'd have an attitude too." Montjeu has swaggered unbeaten through his four-year-old career, with Kinane taunting his opponents through his inactivity. But in the closing days of Montjeu's supposed coronation route to becoming the first sine Alleged (1977-1978) to win back-to-back Arcs, Kinane has been looking over his shoulder again, and what he sees quite rightly worries him. He doesn't have to look very far either. Just to the Curragh where the Epsom and Irish Derby winner Sinndar is, in his own unfussy and easy-going way, practising to push Montjeu off his perch.

At Longchamp eight days ago both had their warm ups. Montjeu was typically extravagant, slicing past inferior opposition with elan. But Sinndar was awesome. No poor horse wins two Derbys but Sinndar now looks as good a racehorse as Ireland has produced in years.

John Oxx describes the possibility of Sinndar crowning himself the best horse in Europe, possibly the world, by beating Montjeu and winning the Arc as "a little spectacular." If ever a statement summed up the Curragh trainer, that's as good as any.

Oxx's determination to avoid the hype trap is only matched by his pragmatism and that's why even he cannot dilute the thrill of anticipation over this race.

"Every day is anxious at a time like this, trying to get the horse to the race in good form, but it's also a very exciting time," he says, not least because Oxx concedes he has not worked with material as good as this before.

"I have to say he is the best I've trained. Sinndar has won two Derbys and he has a chance of running a big race in the Arc," he says. That's no mean statement considering Oxx tutored the Breeders' Cup winner Ridgewood Pearl to world fame but the thing with this colt is that we may not even have come close to seeing the best of him yet.

"If nothing untoward happens between now and then, and he gets the chance to show what he is made of, I think Sinndar will run the best race of his life in the Arc. I'm pretty sure his rating will go up after it," he says. It will need to because the cold eyed international handicappers currently rate Montjeu a 7lb better horse. But the Arc is won when the best horses in Europe turn to face Longchamp's final quarter mile straight and not on paper. And that's why racing professionals are relishing the prospect.

"It looks like it could be a truly fantastic race," says Oxx's Curragh colleague Dermot Weld who confesses he doesn't know which way to cast his vote as to the likely winner. Weld gives honourable mentions to the German champion Samum and the French filly Volvoreta but concedes that attention inevitably has to concentrate on the best horses in France and Ireland.

"Montjeu is an exceptional horse. His performances over the last 18 months prove that. But Sinndar is improving and when a three-year-old, of Sinndar's toughness and class, starts improving like that in the second part of the season, anything is possible," Weld says. Oxx in turn makes no secret of his regard for Montjeu who could deliver a third Arc for his trainer John Hammond, a former student at Dublin's Trinity College.

"Montjeu would have to be on everyone's list of the top 10 horses of the last 50 years. He's up there with the greats. He has speed, stamina and there is no easy way to beat him except through sheer ability. Tactics won't beat him because he can win off a slow or a fast pace. It will just come down to a battle down the straight," Oxx says. And that's where Sinndar's rapidly expanding fan club believe he will play his trump. Like his trainer, Sinndar may be averse to the flash but nothing will ever get by him easily.

"Montjeu possibly has more speed but Sinndar is very, very tough," considers Weld. But against that is the memory of last year's Arc. Montjeu found himself five lengths behind El Condor Pasa as they turned into the straight and then Kinane had to extract him from a pocket. He still won. Montjeu's bottle is as proven as his style. Hammond, however, is under no illusions about the task that lies ahead of his star despite having proved himself last year . "In some ways, it's harder this time," says the Chantilly-based trainer.

Ultimately victory in the Arc can hinge on the swings and fortunes of a checked run or a cut leg or a jockey's impetuosity or any number of chances that cannot be forecast. "I think the going and the tactics used on the day will decide it," declares Weld who has successfully agonised about going tactics around the world. Oxx for his part would worry if the ground at Longchamp came up very testing.

"I think it was fitness rather than the ground that beat him on his first start this year but the record shows the only time Sinndar has been beaten was on heavy going. Montjeu would handle it better whereas we might like faster ground," he says. The beauty of it all, however, is that we will know in the two and a half minutes the race will take to run. In that time no quarter will be asked or given and afterwards no excuses will be needed. Just as it should be.