Victoria Pendleton picked herself off the floor to record a brilliant semi-final victory over Australia's Anna Meares en route to world sprint gold.
Pendleton suffered track burns after a crash in her first best-of-three semi-final heat against arch-rival Meares.
The Briton struck back to reach the final in Melbourne, where officials relegated Lithuania's Simona Krupeckaite to hand her gold.
"It's been an emotional rollercoaster," Pendleton told BBC Sport.
"That's not necessarily the way I'd like to win, in an ideal scenario, with relegations and stuff. It always feels a bit weird and not very true to the sport, but those are the rules.
"I'm delighted with the result. I didn't think it was going to happen coming into today. It's great to end on a high."
Pendleton intends to retire after the London Olympics and will now do so with nine career world titles to her name, including six in the sprint.
To keep her hopes of winning this one alive, she first had to peel her battered right side up from the Hisense Arena track. She clashed arms with Meares in the midst of a frantic finish to their first semi-final heat, sending the 31-year-old crashing down and burning her right shoulder, elbow and hip on the wooden surface.
"It's not too bad. I lost my balance, went too far in one direction and lost my traction," she said.
"My dad always said you don't do track cycling unless you're prepared to crash. I slid quite nicely, which sounds random, and I felt fine. I could tell it was just surface wounds."
Meares told BBC Sport: "I'm getting sick of meeting Vicky in the semi-final, it's making it really hard. For her to pick herself up after that heavy fall and come back as hard as she did is a mark of the woman and the great champion that she is."
Olympic champion Pendleton against world champion Meares is the London 2012 sprint final to which track cycling fans and the media have been eagerly building ever since Beijing 2008, where they finished first and second respectively.
If the Australian has recently appeared out of Pendleton's league on one or two occasions, the latter laid her body on the line to prove more than Meares' match in Melbourne.
Officials relegated Meares from the second heat for straying outside her racing line, levelling the score at 1-1.
Pendleton - burns showing through large holes in her GB skinsuit - then upstaged the 28-year-old Meares in a spectacular deciding heat, winning in a photo finish.
The final against Krupeckaite, last year's silver medallist, felt predestined for Pendleton in front of a muted Australian crowd.
But the victory came in odd circumstances. Pendleton won heat one and Krupeckaite seemed to have levelled in the second race before the Lithuanian, too, was relegated in identical circumstances to Meares.
Pendleton, already off the track and preparing for a deciding heat when the relegation and her consequent victory were announced, fell into an emotional celebration as she won Britain a third gold medal of the week in Olympic events (fourth overall). Meares took the bronze.
"I was disappointed with the team sprint [on Wednesday, when Pendleton and Jess Varnish failed to earn a medal]," said Pendleton.
"It left me flat, I must admit. Picking myself up for this was quite hard. I thought this was going to be a stepping-stone and I hoped I might do a better performance than I did at the London World Cup.
"I feel I did that and I'm more than pleased."
Elsewhere on Friday, Sir Chris Hoy took a lengthy route to the men's sprint semi-finals, where he will now face team-mate Jason Kenny.
The Scot first came through a repechage round following an early defeat by France's Mickael Bourgain, then edged past Germany's Robert Foerstemann in their deciding quarter-final heat, which also required a photo to separate the pair.
Kenny defeated Frenchman Kevin Sireau in their last-eight decider with a bold, early bid for the line to set up an all-British semi-final on Saturday. The outcome of that race could help to decide which of the pair rides in the sprint at the Olympics, with only one slot available.
In the six-event men's omnium, Britain's Ed Clancy lost some ground on his rivals with seventh place in event five, the scratch race, eventually claiming fourth overall despite a strong time trial to finish.
Britain's Dani King took fourth place in the non-Olympic women's scratch race, having been part of the women's pursuit team that won world gold a day earlier.