It takes about 90 minutes to fall in lust with Rio de Janeiro. That's the length of time of a football match, of course, but it's also around the time it took to walk from one of Rio's most beguiling areas to another and back again yesterday morning: from Ipanema to Copacabana.

Feel the heat. Starting off close to the Garota bar, where Tom Jobin infected the planet's consciousness with The Girl from Ipanema so many years ago, strolling along the Avenue Viera Souto with the green Atlantic breaking in a gentle rush onto clean white sands should be enough intoxication for one lifetime; but to then go from there and arrive at such a venue of legend as Copacabana beach, a sports arena every bit as significant as Wembley's twin towers, is to be overwhelmed by atmosphere.

Jealous? You should be. Even the ugly people here are beautiful - Jobin could easily have used the plural in his song title, and there's no doubt, as the song says, that each one she passes goes "aahhh" - and it is a relief to encounter the odd individual who would not look at home on the catwalk. Or indeed to see some mis-control at one of the many mini-matches that pepper the beaches.

For it is no myth: the beach is where Brazilian children, boys and girls, learn to caress heavy leather balls with their bare feet. You could try to avert embarrassed eyes, but it would be difficult, because football is one of the constants on this smooth shoulder of Rio.

Further along the shore, in Sao Conrado, Manchester United have found a most appropriate place to base themselves. Less than 30 minutes bustle through the palm trees and crazy drivers brings them to the Maracana, where tonight United begin the uncertain journey that may see them crowned Club World Champions tomorrow night week.

And maybe it's Rio, or maybe, despite its dilapidated facade, it's the spirit of the Maracana, but there is a discernable sense that United are warming to a tournament they regarded as an elaborate joke until a few weeks ago.

"This is the place," was one of the few, simple but telling remarks Alex Ferguson uttered on first entering the famous stadium. United's chairman, Martin Edwards, in contrast to earlier antagonistic statements about the competition, said yesterday that the best way to approach the event was via a boxing analogy.

"You can feel the build-up now," Edwards said, "there is a sense of occasion about it all. It's like a heavyweight world title unification bout."

There are, particularly in England, many who would like to see United receive a good pummelling. The issue of the FA Cup was raised again yesterday (and it will remain a source of sparring right up until its final on May 20th), but Edwards and Ferguson continued to insist the club's absence was all down to the British government and England's 2006 World Cup bid.

To continue the analogy, United were knocked out - or knocked themselves out - with the decision, but on the other nights that mattered the last eight months of the 20th century saw them collect four belts, and there is therefore a modicum of substance in Edwards' unification claims.

"Last year will never be repeated," he added, "but this is the world stage. This is the first time clubs from the whole world have come together to compete in a league system. That adds prestige. If we win, our reputation will be enhanced throughout the world."

He didn't mention the implications of not winning. Even so, the $3 million guaranteed just by coming second in the group stage must be a comfort for the chairman.

Not that Ferguson has any desire to be a runner-up, but he has sounded a bit like Jack Charlton in Florida by banging on about the temperature his players will have to deal with. Yet at kick-off, 6.15 p.m. local time (8.15 p.m. Irish), anything less than 70F is regarded as cool, so it could be Manchester's undoing, and Ferguson's opposite number tonight, Raul Arias of Necaxa, mentioned it.

"The heat will be on our side," said Arias. "We want it hot because we know that will help us. The English are going to feel the heat a lot more and are not going to be able to deal with a fast rhythm."

The rhythmic beat in the heat was also Ferguson's focus again. "It could be really sticky. The heat might make us change our game a bit, with an emphasis on keeping possession and conserving energy."

That said, Ferguson is aware of United's history of attacking football and he wants "to impress the people of Brazil" with some. "It's important to put on a good show."

It is also important that United win, and for that reason alone Roy Keane is likely to start despite a tender left knee. "We need to go into the Vasco da Gama game with a win," said Ferguson. "That match is the big one."

Already the eyes are on Saturday night's big fight. Presumptuous? We shall see tonight.