Between them Argentina and Brazil have won five of the last six World Youth Cups.
But they made a poor start to the tournament currently being held in Holland.
Fredy Guarin (on knees) is part of Colombia's promising youth team
Neither even managed a goal; Brazil were held to a scoreless draw by Nigeria, while Argentina went down 1-0 to the United States.
Meanwhile, the honours went to the two other South American sides.
Colombia were comfortable 2-0 winners against Italy, and Chile filled their boots with a 7-0 thrashing of Honduras.
These results will come as a surprise to most. But they are perfectly in line with what happened in South America's qualifying tournament in Colombia earlier this year.
Even allowing for home advantage, the hosts were the best team on show, confirming the impression that Colombia have found a generation capable of going on to great things.
Midfield general Aguilar, right back Zuniga and strikers Rodallega and Renteria all looked like class acts.
The strength of the Chile side was its midfield, full of players with ability on the ball. Fernandez and Fuenzalida were particularly impressive.
Both were on target on Saturday against Honduras.
Chile endured some anxious moments before making sure of the last qualification slot, but were it not for a tendency to give away silly goals they would have sealed their place in comfort.
In the decisive stage of the qualifying tournament, Colombia and Chile found goals easier to come by than their illustrious rivals.
In five games they scored 11 and 10 respectively, while Brazil managed eight and Argentina a mere five.
On this weekend's evidence the big two have yet to resolve the problem.
Argentina have axed all the strikers who featured in qualification. Their replacements have yet to do any better, though the introduction of the highly promising 17 year old Aguero might bring about an improvement.
Argentina and Brazil still have ample opportunity to work out their problems
The strikers' task would be eased if Argentina's midfield could occasionally pass the ball over long range.
Even with their flaws, Argentina are well worth watching for the glorious skills of Barcelona's Messi, the outstanding goalkeeping of Ustari and for the commanding centre back Garay, whose absence through suspension was a key factor against the USA.
Brazil seem to have their most ordinary Under-20 team for some time.
They are big, strong and not easily beaten, but there is a worrying lack of midfield creativity about them.
Perhaps the most depressing aspect of contemporary Brazilian football is the lack of central midfielders capable of dictating the rhythm of the game, in the way that, for example, Falc„o and Toninho Cerezo did in the 1982 World Cup team.
Nevertheless, they seem to have found another gem in right back Rafinha. Plenty of scouts will be having a close look at talented but temperamental striker Diego Tardelli.
His strike partner Rafael Sobis is a bright player who is unlikely to have another game as poor as the one he played against Nigeria.
So, Colombia and Chile would seem to offer South America its best chance of winning another title - but rule one of tournaments is that it is a mistake to place too much importance on the opening matches.
In the World Youth Cup 16 of the 24 teams make it through to the knock out stage. It means that one victory from the three group games is usually enough to ensure qualification.
Argentina and Brazil have ample opportunity to work out their problems, grow through the tournament and peak at the right time.
In one crucial aspect they hold the advantage over the likes of Colombia and Chile.
The triumphs of the past have left a legacy of a winning mentality, which means that when it matters most results can be dug out and titles won even when events seem to be going against them.