Milica Mandic won Serbia's first gold medal of London 2012 as she beat Anne-Caroline Graffe of France in taekwondo.
The 20-year-old, who previously won silver at the 2012 European Taekwondo Championships, won the +67kg class 9-7 in the final at ExCeL.
Graffe was the top seed, but Mandic also beat the defending champion and the number two seed on her way to gold.
Russia's Anastasia Baryshnikova and Mexican Maria del Rosario Espinoza won bronze.
Baryshnikova, 21, won gold at the european championships in Manchester earlier this year, but was beaten by Mandic in the semi-finals.
Espinoza, who won gold in Beijing four years ago, was also beaten by Mandic in the quarter-finals.
She then came through repechage to beat Glenhis Hernandez of Cuba 4-2 to secure her bronze medal.