LONDON: Despite a glorious past that includes five World Cup triumphs, Brazil have never struck gold in the Olympics and former striker Ronaldo thinks it is now their time to shine.

The Olympic football tournament will feature some of the world's top names with Brazil, world champions Spain, the old Olympic kings from Uruguay and a rare appearance from host nation Britain, all in with a chance of glory.

Among the leading individuals involved in the men's competition are Brazilians Neymar, Hulk, Thiago Silva and Alexandre Pato, Uruguay's Luis Suarez and Spain's Juan Mata and Jordi Alba, who both scored in their victory over Italy in the final of Euro 2012.

Brazil, naturally, are among the contenders and will attempt to overcome their Olympic nemesis by winning the gold medal for the first time at their 13th attempt since they first competed in 1952.

Former Brazilian striker Ronaldo, a World Cup winner in 2002 and an Olympic bronze medalist in 1996, told Reuters it was Brazil's time to win gold.

“There is no real reason why we fail at the Olympics, which we take very seriously,” he said.

“In some way these are already a successful Games for us because Argentina (winners in 2004 and 2008) were eliminated in the qualifiers and cannot defend their title so now would be perfect if we became champions in their place.”

Brazil face Egypt, Belarus and New Zealand in their opening group.

As in the men's competition, Brazil's women are going for a first Olympic gold and Marta, world player of the year five times, will lead their assault at London 2012.

Brazil's women face Cameroon, New Zealand and Britain in their group games.

The two competitions, comprising 16 men's teams and 12 women's, are among the most complex on the programme with the women starting with six matches on July 25, two days before the Games' official opening. The men start with eight matches the following day.

The first event of the entire London Games is the women's match between Britain and New Zealand on July 25 at Cardiff's Millennium Stadium.

That is one of six venues being used in England, Scotland and Wales along with Old Trafford, Hampden Park, St James' Park, City of Coventry, and Wembley which stages both finals.

While the women's competition will briefly hold the limelight on July 25, most of the attention will be on the men, whose competition is restricted to players aged under 23, plus three over-age players.

Britain also have hopes of gold - which would be its first since 1912.

David Beckham, who hails from East London and was instrumental in helping London win the Olympics, was left out of the Britain squad, but his old Manchester United team mate, Welshman Ryan Giggs, has been included.

The 38-year-old has won more honours in England than any other player.

The relationship between British football and the Olympic Games is so convoluted and politically charged - this is their first finals since 1960 - that even though they are hosts, there was a doubt they would compete.

The problem revolves around independent status issues with FIFA that concern Scotland, Wales and Northern Ireland so whether this Olympic return is a one-off or not remains to be seen. Their group matches are against Senegal, United Arab Emirates and Uruguay.

Uruguay are also returning after a long absence. Their victories in Paris 1924 and Amsterdam 1928, the last time they competed, galvanized FIFA into organising the first World Cup in Uruguay in 1930.

Today's team knocked out champions Argentina in the qualifiers and, led in attack by Suarez of Liverpool and Edinson Cavani of Napoli, the “celeste” will be looking to add the Olympic title to the Copa America they won last year.

Spain, Olympic champions on home soil in 1992 and fresh from their Euro triumph, are contenders again, while teams that could make an impact from Africa, following Cameroon's success in 2000, include Senegal, despite the absence of Newcastle United strikers Demba Ba and Papis Demba Cisse.

The favourites in the women's competition are the United States.

Since women's football was introduced in 1996, the U.S have won three of the four golds and beaten Brazil in the last two finals.

Japan, fourth in 2008, are also in contention while North Korea, banned from the next women's World Cup because of doping offences, will be hoping to make an impact too.