The Olympic football tournament was today thrown into chaos as Argentina insisted Lionel Messi will play in the Games despite Barcelona winning their appeal to have the striker pulled out.

Argentina claim the 21-year-old wants to take part in tomorrow's tournament opener against Serbia despite the Court of Arbitration for Sport backing Barcelona, and German sides, Werder Bremen and Schalke, in their battle over player release.

The clubs argued the participation of Messi and two Brazilians - Bremen's Diego and Schalke's Rafinha - in the Beijing Games over the next fortnight unfairly penalised them for Champions League qualifiers and other matches.

They took the issue to CAS after FIFA had earlier ruled clubs must release all their Under-23 players to play in the Olympics.

CAS secretary-general Matthieu Reeb said the three-man panel ruled in the clubs' favour because the Olympic tournament is not on FIFA's official match calendar. But two hours later, Argentina insisted one of the game's biggest stars will play tomorrow.

Coach Sergio Batista said: "Messi told us he wants to stay. He's relaxed and asks the people at Barcelona to understand his situation. The club arerelaxed and I was figuring to put Messi in the starting 11.

"I am sure he can be here with us for the rest of the competition."

It appears unlikely any other players will be withdrawn as they have the permission of their clubs.

AC Milan's new signing Ronaldinho was released to play for Brazil as one of the three permitted over-23 players.