Angel di Maria's goal gave Argentina its second Olympic football title in a row, a 1-0 victory over Nigeria on Saturday.
Di Maria collected a through ball from Lionel Messi in the 58th minute to give 2004 winner Argentina another gold medal and leave the Nigerians, champions in 1996, the silver.
Brazil won the bronze on Friday by beating Belgium 3-0 in Shanghai.
The only football game to be played in Beijing's Olympic stadium, Saturday's match was watched by a crowd of 89,102 including Argentina great Diego Maradona but hampered by very hot conditions. The referee took the rare step of twice allowing players to stop and take drinks.
This was the first football game to be staged in the Bird's Nest which had the entire playing surface bathed in sunshine at kickoff time. The 90,000 capacity stadium was nowhere near full at kickoff time but had filled up by midway through the first half by which time the heat on the field had built up to 42 degrees Celsius (107.6 Fahrenheit).
After 30 minutes play, Hungarian referee Viktor Kassai took the unusual step of using a free kick stoppage to let players take a two-minute break to drink water and try and cool down. Not surprisingly in the searing heat, the game was poor quality in the first half with too many mistakes, misplaced passes and players trying to move slowly around the field to conserve energy. After Peter Odenwingie's free kick had tested Argentina goalkeeper Sergio Romero into a diving save in the sixth minute, Juan Roman Riquelme fired one over the bar.
Messi had a penalty appeal turned down when he tumbled over Dele Adeleye's challenge and was told to play on by the referee. Nigeria almost went ahead shortly after the drink break when Odemwingie crossed from the left and Promise Isaac just missed the ball in front of goal. The ball came back and Isaac's looping header was saved by Romero above his head.
Argentina, and Messi in particular, were very disappointing in the first half but Di Maria almost made the breakthrough with a 30-meter (yard) shot which Ambruse Vanzekin pushed round the post at full stretch.
Messi produced one of his special moments in the 50th minute when he spun past a defender just outside the area and fired a left-footed drive which Vanzekin punched away.
Then came his pass that set up the goal.
Riquelme went into a tackle inside the center circle and the ball spun out to Messi who immediately released Di Maria clear of the Nigerian defense. The Benfica midfielder had only goalkeeper Vanzekin to beat and nonchalantly lobbed the ball over him into an empty net.
Victor Obinna had a chance to level in the 63rd when he had a clear shot at goal but stabbed it straight at the goalkeeper. Hesitancy by Javier Mascherano in his own area gave Ebenezer Alijore a shot at goal but it rolled wide of the post and then Sani Kaita fired over the bar from the edge of the area.