Hosts Britain, taking part in their first Olympic soccer finals since 1960, will kick off their bid for gold against Senegal at Old Trafford after being placed in a tough opening round group in the draw at Wembley on Tuesday.
Senegal, who play Britain on July 26, reached their first Olympics after beating Oman 2-0 in a playoff on Monday and the group will be completed by Uruguay and the United Arab Emirates.
Like Britain, who won the soccer gold in 1908 and 1912, Uruguay also boast two Olympic titles from 1924 and 1928, and they are returning to the Games after a long absence, in their case 84 years since they won the tournament in Antwerp.
"I saw them play at the Under-20 World Cup and they were very impressive," Britain coach Stuart Pearce told a news conference.
Pearce has a list of 80 probables for his Olympic squad from England, Wales, Scotland and Northern Ireland and can call on leading players from the Premier League.
Luis Suarez of Liverpool could be included in the Uruguay squad and Newcastle United strikers Demba Ba and Papiss Cisse would add considerable firepower to the Senegal team.
"It is such an honour to play against Britain in the opening match at Old Trafford," Augustin Senghor, the president of the Senegalese FA, told Reuters.
"I know we were the last to arrive in these finals after the playoff last night, but I hope that we will not be the first to leave. We will also field our strongest team and see if our players at Newcastle like Demba Ba and Papiss Cisse can be involved."
Seeded Brazil, five-times World Cup winners but never Olympic champions, face Egypt, Belarus and New Zealand in Group C and will play their matches in Cardiff, Manchester and Newcastle.
Their former striker Ronaldo, who played in two World Cup finals and won an Olympic bronze in 1996 at Atlanta, told reporters it was time Brazil finally claimed the Olympic gold.
"There is lots of pressure on Brazil, but we really have to break this taboo.
"It's the only title the Brazil haven't won, so I can say the Brazil team are really motivated," Ronaldo said.
"The Olympic Games is a very important tournament especially for young players who can promote their talents and it is about time we won it."
Brazil actually have the best all-time record in the Olympics having won two silver and two bronze medals without winning the gold.
Spain, who triumphed on home soil in Barcelona in 1992 and are the reigning world and European champions, will play Japan in Glasgow, Honduras at Newcastle and Morocco in Manchester.
Mexico, the other seeded nation will face South Korea, Gabon and Switzerland.
The first event of the Olympics takes place at Cardiff's Millennium Stadium on July 25, two days before the opening ceremony, when the British women's soccer team play New Zealand in Group E. Cameroon and Brazil are in the same section.
Hope Powell, Britain's women's coach said: "Playing in the first event of the Games gives us a great chance to showcase our sport and I am really excited by the prospect of playing it."
Britain will also face Cameroon and there could be a big attendance for their final group match against Brazil at Wembley on July 31.
"Brazil will be a great game for us," Powell added. "They are undoubtedly the tough team in the group, they are always there or thereabouts in major tournaments. We know who we're up against now so it's all about the preparation."
Women's world champions Japan face Sweden, South Africa and Canada in Group F while Olympic champions United States take on France, Colombia and their long-time political foes North Korea in Group G. That match will take place at Old Trafford on July 31.
The group stages of both the men's and women's soccer tournaments will feature two matches in the same stadium on the same day.
The women's final is at Wembley on August 9 followed by the men's two days later.
Olympic football draw
Group A: Great Britain, Senegal, United Arab Emirates, Uruguay
Group B: Mexico, South Korea, Gabon, Switzerland
Group C: Brazil, Egypt, Belarus, New Zealand
Group D: Spain, Japan, Honduras, Morocco
Group E: Great Britain, New Zealand, Cameroon, Brazil
Group F: Japan, Canada, Sweden, South Africa
Group G: USA, France, Colombia, North Korea