Oscar Pistorius was dethroned as young Brazilian Alan Oliveira stole his Paralympic T44 200m crown with a powerful run, topping a successful night on the track for the South American nation.
But the 25-year-old Pistorius hit out after his shock silver that silenced the 80,000-strong crowd at the Olympic Stadium, complaining he was at a disadvantage because of the length of some of his rivals' artificial running blades.
"The IPC (International Paralympic Committee) don't want to listen," the South African "Blade Runner" told Britain's Channel 4 television. "The guys' legs are unbelievably long. Not taking away from Alan's performance, he's a great athlete.
"But these guys are a lot taller and you can't compete with the stride length.
"You saw how far he (Oliveira) came back. We aren't racing a fair race. I gave it my best.
"The IPC have their regulations. The regulations allow that athletes can make themselves unbelievably high. We've tried to address the issue with them in the weeks up to this and it's just been falling on deaf ears."
Pistorius, who had been seeking to defend all three of the T44 sprint titles he won in Beijing four years ago, said US bronze medallist Blake Leeper's knee height, for example, was "like four inches (10cm) higher than it should be".
"The guys are just running ridiculous times and they're able to do so. I think Alan's a great athlete but... I run just over 10 metres per second," he added.
"I don't know how you can come back, watching the replay, from eight metres behind on the 100 to win. It's absolutely ridiculous."
Twenty-year-old Oliveira's unexpected victory was greeted with wild cheering from his compatriots and was the highlight of three golds among five medals for Brazil on the night.
Earlier, Terezinha Guilhermina retained her T11 200m title in a clean sweep of medals that saw Jerusa Geber Santos take silver and Jhulia Santos bronze.
Compatriot Yohansson Nascimento then triumped in the men's T46 equivalent over the same distance in a new world record.
China also had a successful day, with rower Huang Cheng providing a major upset by inflicting the first defeat in British favourite Tom Aggar's five-year international career in the men's arms-only (ASM1x) single sculls.
Huang, 30, said he was "very excited" by his win and after lowering Aggar's world record in qualifying but the British rower, who came fourth, said he was "devastated" to have lost his unbeaten record and Paralympic title.
Elsewhere, in the women's arms-only (ASW1x) single sculls, two-time world champion Alla Lysenko of Ukraine took gold, while Britain gave the home crowd some cheer by taking the legs, trunks and arms (LTAMix4+) mixed coxed four.
Huang's victory was one of two rowing golds for China, with world champions Fei Tianming and Lou Xiaoxian winning the trunk and arms mixed double sculls (TAMix2x).
In athletics, Zhou Guohua won the women's T12 100m for visually impaired athletes in 12.05sec, wheelchair racer Li Huzhao won the men's T53 400m and Gao Mingjie retained his F44 javelin title.
British wheelchair racer David Weir was later roared to victory in the T54 5,000m race and now looks to defend his Beijing 800m and 1,500m titles.
China also won the final C1-5 team sprint on the last day of track cycling to tie with Britain on five golds but the host nation topped the final table with more silver and bronze.
In the pool, stand-out performances included Ihar Boki of Belarus, who picked up his third gold of the Games with a world record in the S13 100m freestyle, while Mallory Weggemann of the United States won the women's S8 50m freestyle.
She complained earlier this week that she had "lost faith" in the classification process after she was moved up a category on the eve of the Games.
Matthew Cowdrey, meanwhile, made it 10 Paralympic career gold medals as Australia won the men's 4x100m freestyle 34 Points relay, leaving him just one gold short of becoming his country's most successful athlete at the Games.
Britain's equestrian riders won their fifth successive team gold. The team included Lee Pearson, who secured his 10th Paralympic gold after losing his 100 percent record over four games at the individual event on Saturday.