Cuban Roniel Iglesias avenged his World Championships defeat from last year
to outpoint Ukraine's Denys Berinchyk and claim light-welterweight Olympic gold.
Iglesias, 23, showed off his silky counter-punching skills to take a one-point advantage after the first.
The Cuban continued to pick Berinchyk, 24, off in the second to extend his lead before taking a 22-15 win.
Great Britain's Tom Stalker went out in the quarter-finals of the division to Mongolian Munkh-Erdene Uranchimeg.
Cuba's boxers went to London fired up to win gold again and Roniel Iglesias has done it in style.
For Cuba, it was a matter of pride. Its boxers have been getting Olympic gold consistently since 1972.
But there were none in Beijing after a series of defections decimated the team.
There were groans here as team-favourite Julio Cesar went out in his first fight, but huge cheers for Roniel Iglesias.
Overall, Cuban boxers are not getting as many medals as they used to. As well as the defections, economic problems are taking their toll.
But Roniel Iglesias has just made the Olympic gold tally for Cuba vs USA 33 vs 34. And on Sunday, Cubans will be rooting for 18-year-old Robeisy Ramirez to even the score.
Berinchyk beat Uranchimeg in the last four to earn his spot in the decider against the man he beat in the first round of the 2011 World Championships in Azerbaijan.
Iglesias, bronze medallist from Beijing 2008 but unseeded in this competition, was made to work for every second of a pulsating clash with the unrelenting Berinchyk constantly pushing him back.
However, the classy Cuban managed to catch the Ukrainian as he came forward with some impressive left uppercuts.
The second round went in similar fashion as Berinchyk showed no signs of taking a backward step - but again Iglesias was too smart and continued to claim points after making his opponent miss.
Berinchyk's attempts turned desperate in the final round as Iglesias was able to extend his advantage and claim a seven-point win.
The Cuban adds London 2012 gold to the World Championship title he won in 2009.