Defending champions Argentina, likely to field two of world football's most exciting and in-demand youngsters, loom as the team to beat again at the Beijing Olympics.
Argentina stormed through the 2004 Athens tournament without losing a match or conceding a goal.
Messi, christened the new Diego Maradona and even endorsed by the football legend as "the player who will inherit my place in Argentina", is so keen to play at the Olympics that he may forgo a UEFA Champions League tie for his Spanish club Barcelona.
Barcelona play their first leg of the Champions League tie on 12 or 13 August, with the second leg taking place on 26 or 27 August.
"I am going to the Olympic Games whatever may happen," Messi said. "The truth is though that I do not know how we can resolve things, but there is no doubt that I will be there. I have really high hopes with the Olympic squad. I am very pleased that Sergio Aguero is joining us and I am looking forward to playing alongside him."
Aguero, who won the Golden Ball as the best player in Argentina's FIFA U-20 World Cup win in Canada last year, recently turned down the opportunity to leave Atletico Madrid for Chelsea after the English club matched Aguero's release clause of €55million.
Argentina national coach Alfio Basile raves about his two dynamos and their pulsating brand of football. "They always astonish me, because they invent something new," Basile said.
The Argentines are also set to call on Liverpool's 23-year-old midfielder Javier Mascherano, who is keen to become the first Argentinian footballer ever to win back-to-back gold medals. "It's important for any athlete to defend the gold medal," Mascherano said. "I might be the only person from my country ever to do it and I'll go down in history, nothing counts for me more than helping my nation."
Argentina launch their campaign against Côte D'Ivoire in Shanghai on 7 August, with the Africans likely to field Chelsea's Salomon Kalou and Didier Drogba and Arsenal defender Kolo Toure. Australia and Serbia are also in Argentina's Group A.
Brazil, who have won five FIFA World Cups™ but not an Olympic gold medal, are in Group C along with hosts China, Belgium and New Zealand.
The Brazilians will be without 2007 FIFA World Player of the Year Kaka after AC Milan's refusal to release him as an over-age player, but Real Madrid defender Marcelo said he wants to be part of history in Beijing.
"If we win gold we will go down in Brazilian national team history. It would be a very special title. I want to make history but first we have to produce the goods on the field," Marcelo said.
But he believes fierce South American rivals Argentina stand in Brazil's path to the gold medal. "Argentina could provide our toughest test because they've got a very strong generation of players like Messi, Aguero, (Gonzalo) Higuain and (Fernando) Gago."
Italy, the reigning FIFA World Cup champions and bronze medallists in Athens, launch Group D against Honduras and are also grouped with South Korea and 2000 Olympic champions Cameroon. The Koreans, however, will be missing Manchester United midfielder Park Ji-sung as an over-age player due to fatigue.
The Dutch are looking to Liverpool winger Ryan Babel to drive them to gold. "With his qualities, Ryan is a vital player for our plans," Holland's Olympic coach Foppe de Haan said.