Bradley Wiggins' rainbow jersey bid was derailed by a blistering ride from Fabian Cancellera and a mechanical problem as the Swiss rider clinched the world time-trial title at the UCI World Road Championships in Mendrisio, Switzerland on Thursday.
Wiggins, who finished fourth in the Tour de France in July, described the event as his final "project" for the season, but - having already been passed by Cancellara despite starting two minutes in front - the 29-year-old Briton was forced to change bikes with less than 10 kilometres remaining.
Olympic champion Cancellera blitzed the 49.8-kilometre route at an average speed of 51.58 kilometres per hour to win in 57 minutes 55.74 seconds, with Sweden's Gustav Larsson 1min 27.13secs behind in second and Germany's Tony Martin third, while Wiggins limped in almost five minutes adrift in 21st, three places behind compatriot Chris Froome.
It was another disappointing day for Britain after Emma Pooley, the Olympic runner-up, finished 11th in the women's time-trial on Wednesday.
Wiggins was a realistic podium prospect, but Cancellera, the world champion in 2006 and 2007, was hot favourite on his home roads in the Italian-speaking region of Switzerland.
And the 28-year-old, who won the Tour de France prologue for the third time in Monaco in July, was 18 seconds clear of the field after the first time check and in sight of Olympic silver medallist Larsson after 16.6km - one lap of the three lap circuit.
Cancellara then chased down Wiggins as his stunning ride continued.
The top step on the podium was Cancellara's, but Wiggins was in contention to join him until mechanical misfortune struck, with the triple Olympic track champion seen flinging his bike away in disgust.
Cancellara avoided any such drama - even allowing himself to celebrate before the line - to triumph and will now target the double in the men's road race on Sunday.
Britain's nine-man squad - minus Mark Cavendish and Wiggins - will be led by David Millar, while Saturday's women's road race team features defending champion Nicole Cooke, Pooley and Lizzie Armitstead in the six-person squad.