Colin Oates moved into the third round of the Olympics men's -66kg judo competition with victory over Australian Ivo Dos Santos.
Oates received a rapturous welcome when he entered the arena at the ExCel Centre and the British fighter took the contest to his opponent, who picked up a passivity penalty midway through the five-minute bout.
Another penalty saw Oates move ahead, which he followed up with a score of his own to record Team GB's first win on the tatami at London 2012.
Oates is now set for what will be a much tougher encounter against Mongolian Tsagaanbaatar Khashbaatar, the world number three and bronze medallist from Beijing.
Sophie Cox bowed out of the women's under-52kg when she lost her opening bout to Ae An Kum of North Korea.
Rochdale-born Cox, who returned to the sport having retired following the Athens Games, battled well during the opening stages.
However, she was caught by a Yuko score with one minute and 45 seconds left by the 2008 Olympic silver medallist, which proved enough for victory.
Cox felt the draw had not been kind to Team GB, saying: "I have found over the last couple of years if I can get through my first fight, then I can go on to do well, so this one was make or break.
"I did not worry beforehand she was an Olympic silver medallist, I just went out there to fight my own fight.
"But I just could not get it right and it was a tough draw. I felt fit and strong, it just did not happen today."