London ? Imagine Ronaldinho taking on Lionel Messi for the Olympic gold medal.

Two of the stars of world soccer and, until recently, Barcelona teammates, could wind up facing each other if Brazil and Argentina meet in the gold medal match in the Olympic stadium Aug. 23.

A meeting of the two traditional South American foes would lift the profile of Olympic soccer, considered an inconvenience by club team coaches.

FIFA, soccer’s world governing body, ruled July 30 that teams must release players 23 and under for the games. Even so, German club Werder Bremen is appealing the decision.

Brazil and Argentina are sending strong lineups to China for the Aug. 7-23 soccer tournament being played in five cities – Beijing, Shanghai, Tianjin, Shenyang and Qinhuangdo.

Although the competition rules state the competition is aimed at players aged 23 or below, the 16 teams are allowed to include three older players. That has given Brazil the chance to select 28-year-old Ronaldinho, who just transferred from Barcelona to AC Milan and Messi, who is only 21, will have the hugely talented playmaker Juan Roman Riquelme as an overage player on the same side.

The Olympic tournament will give Ronaldinho the chance to show he has recovered from torn adductor muscles which sidelined him for the last six weeks of the Spanish season. The former FIFA player of the year had a bad season, losing his impact as a magical dribbler and free kick scorer and accused of too much nightclubbing and putting on too much weight.

Milan coach Carlo Ancelotti said the Olympics offered Ronaldinho “a chance to get back in shape.”

“When he returns he’ll be ready and he’ll only require the time to adapt to our system,” Ancelotti said.

Ronaldinho also will line up alongside his new Milan teammate Pato, although the club’s other star Brazilian forward, Kaka, will not take part in the games. The squad does includes Real Madrid star Robinho, however, and will be one of the big favorites for a gold medal Brazil has never won.

Brazil should cruise through to the quarterfinals, facing modest Belgium, New Zealand and host China in group play.

Argentina, the defending champion from Athens four years ago, has tougher opposition in Ivory Coast, Serbia and Australia.

The United States, which has Freddy Adu on the squad, also has a tough group – Japan, Netherlands and Nigeria. The other group is Italy, Honduras, South Korea and Cameroon.

“It’s a difficult group definitely, but that’s what we expect in a tournament that includes the top 16 teams in the world,” U.S. head coach Peter Nowak said. “They are very quality teams we will face, and we have to be up to the challenge.”

The competition will give Adu a chance to show he still has the talent that made headlines when he emerged as a 14-year-old. The stocky forward has spent the last five years making little progress although he has recently made a breakthrough into the World Cup qualifying squad, setting up the winner for Eddie Lewis in a 1-0 victory over Barbados.

The Dutch and Italians seem to be the leading contenders from Europe, which has not had an Olympic men’s soccer gold medalist since Spain won it on home turf in Barcelona in 1992.

Nigeria famously won the title at the Atlanta Games four years later when Nwankwo Kanu led the team past Brazil in the semifinal and Argentina in the final. Africa kept the title four years later in Sydney when Cameroon beat Spain in the final. Argentina beat Paraguay in an all-South American gold medal showdown in Athens four years ago, Carlos Tevez scoring the only goal of the final.