Fabian Cancellara won his second medal of the Beijing Games with victory in the men's individual time trial.
The 27-year-old Swiss, who claimed bronze in the men's road race on Sunday, clocked a time of one hour, two minutes, 11.43 seconds to win gold.
He finished 33 seconds ahead of Sweden's Gustav Larsson in second while Levi Leipheimer of the US took bronze.
Road race winner Samuel Sanchez of Spain was sixth, while Britain's Stephen Cummings finished in 11th.
It was another disappointing result for Spain's Giro d'Italia champion Alberto Contador and Tour de France runner-up Cadel Evans of Australia.
They now leave Beijing without a medal after finishing fourth and fifth respectively.
In the time trial, 39 riders from 29 countries completed two laps of a hilly circuit between two sections of the Great Wall of China in a 47.3km race against the clock.
Cancellara, who was the last rider to go, made an electric start and by the halfway mark he had already overtaken Stefan Schumacher of Germany, who had started 90 seconds ahead of him.
"I'm very, very happy and very proud of this ride"
Cancellara went into the final quarter of the race trailing Larsson by six seconds but he produced a stunning final quarter to claim his maiden crown.
He punched the air as he crossed the line before staggering off his bicycle and collapsing along some barriers while trainers poured water over him.
"It would take much more than 50km to realise what I did," said Cancellara, who has won the world time trial title for the last two years.
"One hour and 2 minutes is a really, really tough race. Now is the moment to enjoy and to be happy and proud that I won.
"I'm very, very happy and very proud of this ride today and to go home with two medals."
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Leipheimer, whose Astana team was barred from the Tour de France, fought a close race with Contador for the bronze and said it was his life-long dream to win an Olympic medal.
"In the situation I was in, not being able to do the Tour de France, I was really motivated," he said.
"I worked very hard for this and it paid off. I pictured myself on the top step but this is brilliant."
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