A quick qualifying round has whittled down the 38 teams to 32 as action gets under way this week in the Copa Libertadores, South America's Champions League.
Picking a competition winner at this stage is not easy - with the star players constantly moving to Europe, success in South America is very difficult to sustain. The big teams are forever having to rebuild.
Carlos Tevez helped guide Boca to the title in 2003
Sometimes they suddenly find a blend in the middle of the competition, as Boca Juniors found out two years ago.
They struggled through the group phase and looked on their way out when they lost at home to Paysandu of Brazil in the first leg of the second round.
But then Carlos Tevez exploded into form and they won an extraordinary sequence of seven straight victories to take the title.
Last year Boca reached the final once more - their fourth in five years - but never found the same form and were beaten on penalties by Once Caldas of Colombia.
Caldas, from the relatively small town of Manizales, were a well-organised team playing cautious, collective football.
It was a similar model to that used by Olimpia of Paraguay, who eliminated Boca in the quarter-finals on the way to the 2002 title.
This has become the pattern - if the established giants fail to come up to scratch then the smaller clubs are prepared to grind their way towards an upset.
With their recent history in the competition, Boca Juniors are still the team to beat.
But they are in a phase of transition and their great Buenos Aires rivals River Plate have certainly had better sides than their current one.
So this year Brazil could offer a stronger challenge than Argentina. No Brazilian team has lifted the title since Palmeiras in 1999.
Robinho (right) will be key to Santos' success this year
Although Palmeiras are back in the field, the best bet from Brazil would seem to be Santos.
Pelé's old club have picked up some useful experience from their Libertadores campaigns of the last two years.
They are the reigning Brazilian champions and have managed to keep the side together.
Wonderkid Robinho is hungry to win South America's premier club title before moving to Europe.
Full of attacking variations, they confirmed their good form with Sunday's 3-0 win over Corinthians.
But before they can think about winning the competition, Santos first have to concentrate on making it out of their group, which is unlikely to prove entirely straightforward.
Part of the fascination of the Libertadores is that South America is such a vast continent.
There are long away trips and, at the end of them, the visiting team can find a hostile environment and conditions that are vastly different from home.
Brazilian teams hate playing at altitude and Santos have drawn the short straw this year.
They open their campaign on Wednesday away to Bolivar of Bolivia, 3,600m above sea level in La Paz.
Their second away game is just as tricky - only slightly lower down in Quito, the capital of Ecuador - against a dangerous LDU side.
Only Danubio of Uruguay offer a short trip and familiar conditions.
These are the ordeals Santos will have to overcome to get through to the knockout stages. It will not be easy.
There are plenty of interesting outsiders, such as Pachuca of Mexico or Cerro Porteño of Paraguay.
But going into the tournament, Santos are my favourites to win the 2005 Copa Libertadores.