Ireland's Lisa Kearney lost her judo bout today to China's Wu Shugen in the under-48kgs division at ExCeL.
Kearney, from Belfast, who received a bye into the round of 16 went out on the golden score, having entered overtime level with the world number two at one point apiece.
Shugen prevailed after producing an Ippon, a clean throw, which automatically ends the contest.
Russian Arsen Galstyan dedicated his judo gold medal to the victims of the Krasnodar floods after winning the under-60kgs.
The 23-year-old became Russia's first Olympic champion in the sport since the break up of the Soviet Union when he beat Japan's Hiroaki Hiraoka with an ippon score, having dispatched top seed Rishod Sobirov in the semi-final.
"My medal will mean a lot to Russia, especially those who suffered in the floods, and I express my condolences to them," Galstyan said.
"I feel absolutely wonderful and happy to be the person who has brought this medal back to Russia, because we have waited for this a long time."
The world number five added: "I have been training really hard for this and now have the result.
"I cannot really put it into words."
Hiraoka - who had beaten Britain's Ashley McKenzie in the opening round - was forced to again settle for a silver medal, having also finished runner-up at the 2011 World Championships.
He said: "I really wanted to come to the London Games and had worked really hard in the last four years.
"I am still not satisfied with the colour of my medal, but did the best I can."
Double world champion Sobirov had been favourite for gold, but just like in Beijing four years ago, the Uzbekistan fighter had to again be content with bronze after beating France's Sofiane Milous.
"I tried very hard to fight for more than bronze here, but it was very difficult," he said.
Felipe Kitadai of Brazil won the other bronze medal, having come through the repechage fight-off against Italy's Elio Verde.
There was more success for the 2016 Olympic hosts when Sarah Menezes claimed gold in the women's under-48kg after defeating defending champion Alina Dumitru of Romania.
Dumitru, set to retire after the London Games, had earlier seen off the challenge of two-time world silver medallist Tomoko Fukumi in the semi-final.
However, Menezes gradually got on top of what was a tight encounter, landing a crucial scoring throw with under a minute left and followed with another in the closing stages to secure the Olympic title.
"This medal will change my life," said the 22-year-old, now Brazil's first Olympic judo champion.
"I always believed in myself and hope I will be a big example with this gold medal.
"I am looking forward to Rio de Janeiro, 2016."
Dumitru, 29, was content to be calling time on her judo career with another Olympic medal.
She said: "I have been to the Games twice and now have two medals, which is great.
"For me it is the last one because I want to start a family."
There was, however, more disappointment for Japan as world number one Fukumi was then beaten on golden score by Eva Csernoviczki of Hungary - who had been strangled unconscious during an earlier bout - in the bronze-medal fight-off.
Csernoviczki admitted she knew little about the incident, which happened in her quarter-final against Belgian Charline van Snick, who also went on to win bronze through the repechage.
"I did not know I had been (knocked) out and stood up, ready to fight again," she said.
"It was very hard for me, but my coach said just to focus on the next match and I was able to stay relaxed when I fought for bronze."
Tomorrow sees the under-66kgs men in action, when Russian Musa Mogushkov will look to justify his Olympic selection ahead of world number one Alim Gadanov, while Japan's Masashi Ebinuma and Mongolian fighter Tsagaanbaatar Khashbaatar will also look to make an impact on the medal stages.
In the women's under-57kgs, Beijing 2008 bronze medallist and reigning world champion Misato Nakamura of Japan will lead the challenge for gold.