Romanian shooter Alin George Moldoveanu won a titanic tussle with world number one Niccolo Campriani of Italy to claim gold in the men's 10m air rifle.
Moldoveanu held his nerve with a final shot of 10.3 to hold off his rival, who finished just 0.6 points behind.
The duo both topped the qualification by equalling the Olympic record and swapped top spots in the final a number of times before Moldoveanu prevailed.
Behind Campriani, Gagan Narang won a bronze medal for India, which was some consolation for the hundreds of Indian supporters crammed into the rifle range after Abhinav Bindra's early exit.
Bindra won India's first individual gold medal at Beijing four years ago but could only finish 16th in qualifying.
Elsewhere, Japan's Kaori Matsumoto looked a strong shout for gold in the women's under-57kg judo after beating Italy's defending champion Giulia Quintavalle to reach the semi-finals at ExCeL.
Matsumoto, the 2010 world champion and runner-up last year, was given a stiff test by Quintavalle before the Italian faded and lost by waza-ari.
Japan have never had an Olympic finalist in Matsumoto's division, but the 24-year-old will make the breakthrough should she beat Automne Pavia of France in the last four.
American Marti Malloy knocked out the second-seeded Telma Monteiro from Portugal in the first round and then rolled past Russia's Irina Zabludina to reach the semi-finals, where Romanian Corina Caprioriu stands in her way.