The biggest fencing upset of the Games so far was a self-inflicted wound by women's sabre fencer, flag-bearer, and gold medal favourite Mariel Zagunis, 27, of the United States.
In a spectacular collapse Zagunis, who needed just three more touches, or points, to make it into the gold medal match, went from leading South Korea's Kim Jiyeon 12-5 to losing 15-13.
Her attempt to win a third straight individual gold medal was compounded by a loss in the bronze medal match, meaning the world number one came away empty handed.
"She didn't beat me, I beat myself," Zagunis said after her semi-final match with Kim.
"I lost concentration. I probably thought I had it," she said with a sharp edge of disgust in her voice.
Zagunis won gold in Athens after being a last minute entry and repeated that feat in Beijing.
Losing on the Olympic stage is a new experience for the American who, with two world championships to her name, is practically the only fencer to earn a living in what is considered a minor sport in the United States.
For Kim, 24, the medal was completely unexpected as she had never fought back from such a large deficit and converted it to a win before. She was seeded fifth in the competition.
"This is an extraordinary experience. Yes, this is an unexpected win for me," she said while eyeing a group of South Korean reporters waiting for their new national hero to speak.
The triumph was even more poignant given that two nights ago team-mate Shin A Lam was caught up in a technical snafu that probably cost her a chance to contest for gold in women's epee.
South Korea's protest left Shin, 25, sitting alone on the dramatically spotlit piste, pristine in her white national uniform but with anguish and desolation written on her face in one of the most indelible images of the Games.
Fencing's governing body on Tuesday offered Shin a consolation medal for sportsmanship, a gesture that all but conceded it was their mistake. Her team mate did not think it was worth much.
"I was there and crying too. It made me want to try even harder to win," said Kim, her sabre gold medal around her neck, having beaten Russia's Sofya Velikaya, 27, the reigning world champion, 15-9.
Olga Kharlan, 21, of Ukraine beat Zagunis for the bronze 15-10. Zagunis said she would now push to make the Rio de Janeiro Olympics in 2016.
Venezuela's Ruben Limardo Gascon won the nation's first gold in 44 years and their first fencing medal at a Games by beating Bartosz Piasecki of Norway 15-10 in the epee.
"I turn 27 in two days. This is the best birthday gift I could ever had given myself," Limardo Gascon said.
The silver marked Norway's first Olympic fencing medal and for Piasecki, a high school maths teacher who heads back to the classroom in two weeks, an unexpected prize.
"A silver medal is unbelievable. I was 23 on the (seeding) table but I am 47 in the world. Now I am top two in the Olympics," he said, adding that the win had yet to sink in.
"That's sports. The favourites want to win the medals. I was just fencing and I was relaxed all day," Piasecki, 25, said.
The men's epee field had been turned upside down earlier on Wednesday when Seth Kelsey of the United States beat world number one Nikolai Novosjolov convincingly in the early rounds with Estonia Prime Minister Andrus Ansip watching.
However, South Korea came away with their second medal of the night after Jinsun Jung, 29, beat Kelsey.
In the bronze medal match, Kelsey, 27, signalled to his opponent that he would be willing to move directly to sudden death extra time as they were tied at 11 even.
"I asked the guy if he wanted to go one touch and he said yes," Kelsey said, adding: "It's an Olympic medal all in one touch. It's very exciting."
Asked if he was a gambler by nature, the behavioural science major who graduated from the US Air Force Academy, quipped: "I'm too poor."
Great Britain's Sophie Williams, meanwhile, is already targeting the next Olympics in Rio after going out in the first round.
The 21-year-old lost 15-6 to the Italian Irene Vecchi – ranked sixth in the world – at the ExCel.
And despite being picked ahead of more experienced fencers, such as Chrystall Nicoll – who went on to appeal against her selection – and Joanna Hutchison – Williams refused to let the occasion get to her.
"It was what it was, it happens in every sport. I did not let it get to me much. I know why I was chosen," she said.
"It was incredible. Everyone gave so much support. It was an amazing atmosphere – so overwhelming. I am just disappointed I did not put in a better performance.
“Hopefully in four years I will come back and put in a better performance. I have been watching for four days and I just wanted to get out there and fence."
Her Great Britain team-mate Louise Bond-Williams also followed her out of the competition at the same stage.
She lost 8-15 to world number four Vassiliki Vougiouka of Greece.