World taekwondo champion Joel Gonzalez Bonilla claimed Olympic gold with victory over South Korean Lee Daehoon in the final of the men's flyweight under-58kg.
The Spaniard, who successfully defended his European title in Manchester earlier this year, had been in good form all day and an early head kick, given on video review, saw him move 5-2 ahead after the first round.
Lee won bantamweight gold at the 2011 World Championships but showed his talent at this lower division as he produced a shock result earlier to put out third seed Pen-Ek Karaket of Thailand.
However, the 20-year-old could not claw back the deficit and was caught by another big head shot in the last round as Bonilla delivered Spain's first taste of Olympic taekwondo gold with a 17-8 victory.
Bronze went to beaten semi-finalist Russian Alexey Denisenko - who had knocked out second seed Wei Chen-Yang of Chinese Taipei in the quarter-finals on sudden death score - after he overcame repechage winner Safwan Khalil of Australia.
Colombian 19-year-old Oscar Munoz Oveido also claimed bronze after he saw off Karaket - who had what would have been a winning head kick at the buzzer correctly overturned by video review.
Earlier, China's Wu Jingyu successfully defended her under-49kg Olympic flyweight title with victory over veteran Spaniard Brigitte Yague Enrique.
The world number one had stormed through the opening rounds, and stopped her semi-final early with a convincing 19-7 victory over Lucija Zaninovic of Croatia.
Yague Enrique, a three-time world champion herself, had come from behind in her semi-final with an amazing late rally against Chanatip Sonkham.
The 31-year-old - who missed the Beijing Games through injury - soon trailed again, as Wu opened up a 4-0 first-round lead.
This time, there was no way back as the 25-year-old Chinese fighter closed out what was in the end a comfortable 8-1 victory.
Thailand's Sonkham, who had beaten number two seed Shu Chun-Yang of Chinese Taipei in the quarter-final, claimed bronze with victory over repechage winner Elizabeth Zamora Gordillo of Guatemala, who had lost to Wu in the first round.
Zaninovic - whose twin sister Ana fights at under-57kgs tomorrow - picked herself up to win bronze when she beat Mexican Jannet Alegria Pena on golden score.