Frenchman Boladé Apithy stunned world number one Eli Dershwitz to claim gold at the International Fencing Federation Sabre Grand Prix in Moscow.
The 33-year-old recorded a 15-10 victory over the American top seed in the final at CSKA Arena.
The triumph marked one of the biggest victories of Apithy's career.
The four-time European Championships medallist had defeated Germany's Max Hartung 15-13 to reach the tournament's showpiece encounter.
Dershwitz, who was aiming to build on the gold medal he clinched at the Sabre Grand Prix in Seoul in March, overcame Italian Luca Curatoli 15-12 in his semi-final.
Hartung and Curatoli finished the event with bronze medals following their respective semi-final defeats.
The women's tournament in the Russian capital got under way today.
Olympic individual silver medallist Sofiya Velikaya of Russia will take on Charleine Taillandier of France in the first knockout round.
The women's medal matches will be held tomorrow.