GROUP A
Team GB 1-1 Senegal
Liverpool striker Craig Bellamy scored the first Olympic goal for Stuart Pearce's Team GB, but it was not enough to secure victory against Senegal at Old Trafford.
Bellamy rifled in the loose ball on 20 minutes after a cross from Manchester United's Ryan Giggs was not cleared.
It was the first goal at the Olympic Games for Great Britain since 1960 – when they last entered a team in the event.
A lively Senegal team claimed a deserved equaliser with eight minutes remaining, Moussa Konate deftly clipping the ball over Jack Butland following Sadio Mane's astute pass.
Marvin Sordell struck the bar for GB in the closing minutes, but they had to settle for a draw in their Group A opener.
United Arab Emirates 1-2 Uruguay
Uruguay took the Group A initiative as they came from behind to beat a spirited UAE side.
Captained by Liverpool's Luis Suarez, Uruguay were favourites, but they fell behind to Ismaeli Matar's first-half goal.
Gaston Ramirez fired in an equaliser before half-time and after the break substitute Nicolas Lodeiro hit the winner.
GROUP C
Brazil 3-2 Egypt
Manchester United's Rafael was among the scorers for highly fancied Brazil, but they were made to work hard as Egypt staged a strong comeback in the Group C opener.
New Chelsea signing Oscar set up the first two goals for Brazil, putting Rafael through to open the scoring after 16 minutes then providing the pass for Leandro Damiao 11 minutes later.
Neymar headed a third and the match looked over, but after the break Mohamed Aboutrika and Mohamed Salah scored to set up a tense finale.
Belarus 1-0 New Zealand
Elsewhere in Group C, Belarus saw off a New Zealand side featuring Ryan Nelsen of Queens Park Rangers and Chris Wood of West Bromwich Albion.
Wood forced a save from Belarus keeper Aleksandr Gutor, but his side were ultimately beaten by a header from Dmitry Baga.
GROUP D
Spain 0-1 Japan
Juan Mata of Chelsea and Manchester United keeper David de Gea could not stop Spain falling to a surprise defeat by Japan.
Yuki Otsu scored the only goal of the match on 34 minutes to settle the match on a poor afternoon for Spain, who also had Inigo Martinez sent off before half-time.
Honduras 2-2 Morocco
Honduras and Morocco played out an entertaining match, Abdelaziz Barrada putting the African side ahead with an sublime volley in the first half.
Jerry Bengtson equalised for Honduras with a 56th-minute tap-in, then struck a penalty to put them in front nine minutes later – Zakaria Labyad levelled before Morocco's Zakarya Bergdich was sent off.
GROUP B
Mexico 0-0 South Korea
Gabon 1-1 Switzerland
It is all square in Group B after both the opening matches finished level.
Park Chu-Young of Arsenal could not inspire his side to make the breakthrough against Mexico.
Switzerland were pegged back after Admir Mehmedi's early penalty by an equaliser from Pierre-Emerick Aubameyang.
