Bradley Wiggins claimed a British record seventh Olympic medal with a sensational gold in the men's time trial.
The Tour de France winner stopped the clock at 50 minutes 39 seconds for the 44km course.
This was a convincing 42 seconds quicker than Germany's world champion Tony Martin, and 68 seconds faster than British team-mate Chris Froome, runner-up to Wiggins in Paris 10 days ago.
Wiggins' seven Olympic medals - four golds, a silver and two bronzes - give him one more than rowing great Sir Steve Redgrave.
"I don't think my sporting career will ever top this now," said Wiggins. "That's it. It will never, never get better than that. Incredible.
"It had to be gold today or nothing. What's the point of seven medals if they're not the right colour?
"The main number is that is gold number four. So I have got to carry on to Rio now and make it five. Just to be mentioned in the same breath as Sir Steve Redgrave and Sir Chris Hoy is very special."
Comparisons between different eras and sports are notoriously subjective, but Wiggins' results in 2012 put him among a select group of British sports heroes.
His victory at the Tour, the first by a British rider, was already an achievement of historic proportions, but to back that up with a fourth gold medal - in three different events, across three Games - is unparalleled in cycling history.
At the 2000 Sydney Olympics he was part of the group that won the bronze medal in the team pursuit event, following that up in Athens by becoming the first Briton in 40 years to win three medals at a Games, before winning the pursuit and team pursuit in Beijing.
British trailblazer Chris Boardman, whose 1992 individual pursuit gold inspired a young Wiggins, is in no doubt as to where the 32-year-old Londoner's achievements should be ranked.
"His sporting performances this year have been unprecedented," said Boardman. "The greatest British cyclist of all time, I have no qualms about saying that. One of the top British sportsmen, also."
Unbeaten in time trials of this distance since losing to Martin at the 2011 World Championships in Copenhagen, Wiggins came into this race as the bookies' favourite. That status might faze some, but the Chorley-based cyclist has been dealing with rising expectations all year.
Marginally down on his German rival at the first time check at 9km, he did not panic. His body position, all important in this discipline, remained perfectly aerodynamic as he turned his pedals with unmatched efficiency and power.
By 18km, he was 11 seconds up; at 29km, his lead was 23 seconds. There was no catching him then, as he was roared home by a massive crowd.
What was in doubt, though, was if the Kenyan-born Froome could claim a one-two finish to match the pair's Tour de France exploits.
But the impressive Martin, who has suffered two serious injuries this season, gritted his teeth to split the Team GB stars.
Taylor Phinney picked up a second fourth-place finish in London 2012's road cycling events - an agonising return for the talented American - while defending champion Fabian Cancellara could only manage seventh.
A special mention also to Luis Leon Sanchez Gil. The unfortunate Spaniard, an outside medal hope, saw his chain snap as he accelerated away from the starting ramp, before puncturing a tyre out on the course.
But this day belonged to one man, the owner of what French newspaper L'Equipe has described "as the most famous sideburns since Elvis Presley", and probably the recipient of British sport's next knighthood.