Great Britain's Sarah Storey claimed her second Paralympic gold medal of London 2012 on day three of competition at the velodrome.
The 34-year-old from Manchester successfully defended her C5 three-kilometres individual pursuit title on Thursday's opening day and on Saturday claimed the ninth Paralympic gold medal of her distinguished career.
The swimmer-turned-cyclist clocked 36.997 seconds to triumph in the women's C4/5 500metres time-trial, arguably the weakest of her four events, in front of an ecstatic partisan crowd.
C5 rider Jennifer Schuble of the United States clocked 37.941secs to place second, with China's Ruan Jianping third in a C4 world record of 38.425, factored to 38.194.
Storey is now set to turn her attention to the road race and road time-trial at Brands Hatch next week, where double gold would see her equal Baroness Tanni Grey-Thompson's British female record of 11 Paralympic gold medals.
It was the second gold of the day for the Storeys, after her husband Barney piloted Neil Fachie to win gold in the men's blind and visually impaired tandem one-kilometre time-trial.
Asked about the husband and wife success, Storey said: "It's amazing. I'm so proud of him and all he has achieved. I just loved it."
Jon-Allan Butterworth won men's C5 four-kilometres individual pursuit silver, clocking four minutes 39.586 seconds, but Australia's Michael Gallagher held off the charge to win in 4mins 35.297secs.
Jody Cundy bounced back from disappointment in his favoured event to claim bronze in the men's C4 4km individual pursuit.
Cundy clocked 1:05.317 after 1km - a time good enough to win one-kilometre time-trial gold on day two, when officials ruled he could not restart - before catching Colombia's Diego Duenas little more than a lap later.