Defending champions Argentina, fielding two of world football's most exciting and in-demand youngsters, loom as the team to beat again at the Men's Olympic Football Tournament in Beijing.
Argentina stormed through the Athens 2004 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 forego 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. The Olympic tournament runs from 7 August to the final on 23 August.
" ," 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 rich English club matched Aguero's release clause of €55 million.
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."
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.
"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.
Nigeria, who were the first African nation to win Olympic gold in Atlanta 12 years ago, are drawn alongside the Netherlands, Japan and the USA in Group B.
The Dutch are hoping Liverpool winger Ryan Babel will recover from torn ankle ligaments to play for them.
"If Ryan is fit, he will be at the top of our list for the Olympics. With his qualities, Ryan is a vital player for our plans," the Netherlands' Olympic coach Foppe de Haan said.