Irini Merleni became the first female wrestling champion in Olympic history by edging out Japan's Chiharu Icho in a thrilling 48kg freestyle final.
There was better news for Icho's sister Kaori, who saw off American Sara McMann in the 63kg-class final.
And Japan's Saori Yoshida beat Canadian Tonya Verbeek to take 55kg gold.
China's Xu Wang won the last Olympic title of the day, fending off Gouzel Maniourova for 72kg gold after winning a controversial semi-final.
Earlier, Xu had ousted Japan's five-time world champion Kyoko Hamaguchi, who eventually took bronze.
Hamaguchi claimed her opponent was unfairly awarded two points for a move which she started, and although no protest was lodged, her father had to be restrained.
"Animal" Hamaguchi, a former professional wrestler, tried to leap from the stands, shouting: "That's impossible - they've made a mistake."
Security guards had to restore order as the 56-year-old man then became embroiled in an angry exchange with his wife, who was doing her best to calm him down.
Hamaguchi, who carried the Japanese flag at the opening ceremony, was favourite to win heavyweight gold.