Mark Cavendish's thunderous face as he finished 29th in the Olympics men's road race Saturday told the story of a ferocious sprinter accustomed to gleefully reeling in his prey in the closing stages.

With a world-class team helping him, a home crowd roaring him on at every corner and fired up by a Britain's recent one-two in the Tour de France, the gold seemed destined for the world champion.

Until a 32-man breakaway of the highest quality decided to up the tempo that is.

Attack-minded Kazakh Alexandre Vinokourov upset the planned sprint finish for Cavendish to take the gold, with Colombian Rigoberto Uran second and Norway's Alexander Kristoff third. So often reeled in by the peloton, this time the riders at the front notched up a triumph on the biggest stage to leave the medalists beaming and Cavendish seething.

"We expected teams to come and chase at the end with us. We controlled it with four guys for 250km and we couldn't do more. We are human beings," said Cavendish, who had a look of disgust on his face as he crossed the line.

American Chris Horner said Cavendish was a victim of his own success over the past few years that has including racking up 23 Tour de France stage wins and the world road race championship last year.