Iran's Hadi Saei defeated Italy's Mauro Sarmiento to take gold in the men's 80kg taekwondo after Britain's Aaron Cook missed out on a bronze medal.
Saei secured a tight 6-4 win, adding a second gold to his 68kg category title success from Athens in 2004.
Earlier, Cook had missed out on a medal after a 4-1 defeat by China's Zhu Guo.
The 17-year-old - who narrowly missed out on a place in the final - fought bravely against the home favourite, but failed make most of his attacks count.
Cook was denied two early points when a headkick was ignored, but was deducted a point for two minor penalties during the second round.
But Guo counter-attacked as Cook looked for the decisive kick to win the match.
A devastated Cook said he was aghast with the judges' reticence not to award points following good attacks.
"They were not putting anything up, I knew the crowd would be (partisan), but not the judges, it was that bad," he told BBC Sport.
"What did I have to do to score a point? I was so tired towards the end, I had nothing left. "I gave it my all, I'm so gutted. I have to go back and do more training. In four years I will be definitely be in first place winning."
The defeat was a bitter blow to Cook, who was so close to booking his place in the final following a hard-fought encounter against Sarmiento.
The semi-final match had been level going into the final five seconds, but the Italian - who had beaten two-time Olympic champion Steven Lopez in the last eight - scored the crucial kick to earn him a place in the final.
It was a cruel blow to the 17-year-old from Dorchester, who thought contact had been made after the final buzzer.
"I'm not happy because from my point of view it was after the bell," Cook's coach Nelson Miller had said after the match.
"The referee made a mistake but that was the best performance ever by Aaron Cook. I'm not disappointed."
Lopez had earlier earned the second bronze medal after a 3-2 victory over Azerbaijan's Rashad Ahmadov.
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