France judo heavyweight Teddy Riner delivered Olympic gold with victory over Russian Alexander Mikhaylin at ExCeL.
Riner may only be 23, but he already has five world titles and had claimed bronze on his Olympic debut in 2008.
Bronze medals went to world number two German Andreas Toelzer, a defeated semi-finalist and third seed Rafael Silva of Brazil, who came through the repechage.
Cuba's Idalys Ortiz, bronze medallist in Beijing, claimed the women's over-78kgs title after she was awarded a judges' flag decision over Japan's Mika Sugimoto following a scoreless contest.
Defending Olympic champion Wen Tong of China was beaten in the semi-final by Ortiz, but recovered to win bronze, as did Great Britain's Karina Bryant, who had lost against Sugimoto.