BEIJING - Football is set to break from its traditionally low Olympic profile in Beijing thanks to the presence of Argentina's Lionel Messi and Brazil's Ronaldinho, two of the game's top players.

The tournament, which kicks off on Thursday with all 16 teams in action, boasts one of the most impressive line-ups in its 100-year history with Argentine forward Sergio Aguero, Brazilian teenager Alexandre Pato and U.S. prodigy Freddy Adu among the other players set to take part.

But far from calming the controversy over whether football should be part of the Games, the presence of so many top players has stirred it up.

Three clubs have appealed to the Court of Arbitration for Sport against a FIFA rule which obliges them to release under-23 players including Barcelona, who want Messi to return to Spain.

CAS is due to decide before Thursday's games.

FIFA president Sepp Blatter said on Monday that directors from football's governing body would meet with their counterparts from the International Olympic Committee after Beijing to discuss football's Olympic future.

"To avoid any misunderstandings for 2012, it has been decided that each item relating to the presence of football at the Olympic Games shall be discussed immediately after the 2008 tournament," he said.

Blatter did not enlarge on what alternative suggestions would be put forward to the current format which restricts the tournament to under-23 teams with three overage players allowed per side.

IOC president Jacques Rogge has already said he wants a new deal for the sport.

"My dream is for all the stars of football to be at the Olympics, because in all the other sports the best are there," he told the German Bild am Sonntag newspaper in March.

EASTERN EUROPE

Despite being an Olympic sport since 1908, football has often sat uneasily at the Olympics and many feel its presence is an anomaly.

Until 1980, the Olympic tournament was officially amateur but, in the period after the Second World War, Eastern Europe countries fielded their strongest national teams, saying that their top players were not professionals.

When professionalism came to the Olympics, FIFA were faced with the possibility of a rival to their own World Cup and responded by imposing an under-23 age limit.

Argentina, who play Ivory Coast in Group A in Shanghai, are strong candidates to retain their title while their arch-rivals Brazil stand out as their main challengers.

Brazil have never won an Olympic gold and are so determined to put that right that senior coach Dunga has taken charge of their team.

They face Belgium in Group C in Shenyang in the first half of a double bill which will be completed with hosts China facing New Zealand.

Thursday's games also see 1996 champions Nigeria face European under-21 champions Netherlands in a Group B match in Tianjin while 2000 winners Cameroon take on South Korea in Qinhuangdao in Group D.