For both Argentina and Brazil, preparation for the Olympic football tournament has been hampered by the need to battle with European clubs over player availability.
Liverpool's Javier Mascherano is in Argentina's squad for Beijing
In theory, there should be automatic release for players of 23 and under. Even so, Germany's Werder Bremen are reluctant to let Diego play for Brazil in China, and Barcelona are determined to hang on to Argentina's Lionel Messi.
But the real problems are with the three permitted over-age players, where the clubs have no obligation to release.
Brazil drew a blank on Kaka, but Milan are prepared to cede Ronaldinho.
Robinho of Real Madrid is also in the squad, but his camp last week were hinting heavily that he would be willing to miss out on the Olympics if a move to Chelsea goes through.
Coach Dunga was anxious to take an experienced centre-back to China, but was unable to secure the release of either of his senior duo, Lucio and Juan, so the classy home-based Thiago Silva comes in.
Argentina also had problems at centre-back. They wanted Martin Demichelis of Bayern Munich, and were turned down.
Inter Milan would not release Nicolas Burdisso and Real Madrid held on to Gabriel Heinze, so the little-known Nicolas Pareja of Anderlecht is one of their over-age players.
The other two are midfielders: playmaker Juan Roman Riquelme of Boca Juniors, and Javier Mascherano, who Liverpool seem set to release with surprisingly little protest, especially as they also lose Lucas Leiva to the Brazil squad.
Mascherano already has an Olympic gold medal from the Athens Games. The fact that he is prepared to trot half way round the world in search of another one begs the question - why is the Olympic tournament so important to the South Americans?
The reasons are threefold.
Firstly, Olympic football has huge historical resonance in South America.
According to some dark voices, success in China is the only thing which will keep Brazil coach Dunga in a job
The Paris Games of 1924 marked the birth of modern football. Uruguay arrived as unknowns, cruised to the gold with a balletic and skilful style Europe had never seen before, and set off a fever for the game.
As a direct consequence of Uruguay's 1924 triumph, and their win over Argentina four years later in Amsterdam, the World Cup came to life.
To this day South American football makes reference to 'Olympic goals' (straight in from a corner) and 'Olympic laps' (of honour, after winning a trophy).
In the here and now, the Olympic tournament represents a chance of claiming a title - and anyone who thinks South American football prizes fun and self expression over collecting trophies is seriously deluded.
The Olympic gold is the only title Brazil have never won, and they are desperate to put that right and complete the set.
Argentina, of course, are the reigning champions. But they still want more - especially as they have a new coach, 1986 World Cup midfielder Sergio Batista, in charge of their youth sides. A win will establish him in his new post.
Dunga, Brazil's senior coach, is also in charge of the Olympic side, and with his team struggling so badly in World Cup qualification, success in China will do wonders for his prestige - according to some dark voices, it is the only thing which will keep him in a job.
Perhaps more important than the title itself is the fact that the Olympic tournament is a halfway house on the road to the next World Cup.
At senior level, for example, Brazil's recent midfield play has been grotesque. In China, the likes of Anderson, Lucas and the talented Hernanes of Sao Paulo will have a chance to bring some more imagination to this vital sector, which could then kick-start the World Cup qualification campaign.
For Argentina the giant Ezequiel Garay could establish himself in the centre of defence, where the team have struggled for height in recent times.
Left-back has been another problem position - Fabian Monzon has an opportunity to solve it.
So there are some important things at stake between the 7th and the 23rd of next month - possibly too important.
Does the Olympic tournament put an extra strain on elite players already suffering from an over-cluttered calendar?
Would it not be better as a pure youth competition, with no over-age players and restricted to under-20s?
A debate is needed, if only to avoid a repeat of the confusion over release obligations which has complicated the preparation of both Brazil and Argentina.
You can put your questions to Tim Vickery every week on the World Football Phone-in on BBC Radio 5 Live's Up All Night programme from 0230 to 0400 BST every Saturday. You can also download last week's World Football Phone-in Podcast.
How do you rate the two South American players, Carlos Villanueva from Chile and Segundo Castillo from Ecuador, that Blackburn are supposed to be interested in? Do you think they'll make the jump to the Premier League? Villanueva especially seems a gamble as he's had no experience of European football before. Alan Sheppard
They're both midfielders, but are very different players. Castillo is only 26, but has much more experience. An established international - 33 caps - he had a good World Cup, and was picked up by Red Star Belgrade. He's a defensive midfielder, a battler, with no great class but very strong and athletic.
Villanueva is the opposite. He's 22, has been an international for little more than a year (nine caps) and is a slight figure - but with real quality in his left foot. He can feature either as a playmaker or can play wide left, where he's not lightning pace but can curl in some lovely crosses. Can he up the rhythm of his game and can he cope with the physicality of the Premier League? I would love to think that he can - if so he can be a real asset to the English game - but Chileans are not always the best of travellers and I have to agree with you that he's a gamble.
I was wondering if you could shed any light as to the potential of the new Liverpool goalkeeper Diego Cavalieri. Brazil is not exactly renowned as a hotbed for good goalkeepers with the possible exception of Taffarel. The most recent high-profile Brazilian keeper, Dida does not exactly inspire confidence. Mike Byrne
I think your comments on Brazilian keepers are a bit out of date - and harsh on Dida, despite the odd blunder. I agree, Taffarel was great, but there's no doubt that Dida did more in Europe, and he had an excellent World Cup as well. In recent years Brazil has become a hotbed of keepers - they are now exporting them all over Europe, and it's no coincidence. They've worked really hard at their goalkeeping preparation, and lots of their keepers now are big and athletic.
Personally I don't rate Diego Cavalieri among the best of them. In my view he's good but not great - certainly not one of the most athletic keepers. In fact he's reminded me of a Brazilian Paul Robinson. I also wonder about the fee. He lost his place at Palmeiras to Marcos, Brazil's 2002 World Cup keeper who had a bad run with injuries. Marcos is a top keeper, but he is now a veteran. Diego was a back up to a 35-year-old, and I'm not sure this fact is reflected in the fee.
Got a question about South American football for Tim Vickery? Email him at firstname.lastname@example.org
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