Britain took a shock gold in the men's Olympic 4x100 metres relay on Saturday, pipping favourites the United States by one hundredth of a second.

Mark Lewis-Francis held off 2000 Olympic 100 metres champion Maurice Greene in a blistering last leg to clinch the gold in 38.07 seconds. It was Britain's first gold in the event for 92 years.

"We have gone and proved everyone wrong, all the people who were talking negative about us," said Lewis-Francis.

The U.S. quartet had to be content with silver in 38.08 seconds with Nigeria taking bronze in 38.23.

It was only the second time in Olympic history that the U.S. team had been beaten across the line in the men's 100 relay.

Canada beat them in 1996 and they have either dropped the baton or been disqualified on the only other occasions they did not take gold.

Britain's only other victory in the event was when it was first staged at the 1912 Olympics in Stockholm.

Saturday's triumph was extra sweet for two members of the British team, Darren Campbell and Marlon Devonish who ran the second and third legs respectively.

They were part of the quartet who lost their silver medal from last year's world championships after final-leg runner Dwain Chambers tested positive for the designer steroid THG (tetrahydrogestrinone). In that race the Americans took gold.

But after a searing first leg by men's 200 metres champion Shawn Crawford on Saturday, the second and third legs run by 100 metres champion Justin Gatlin and Coby Miller left the Americans barely on terms at the final changeover.

Smooth changes from lead-off man Jason Gardener, Campbell and Devonish gave Lewis-Francis, Chambers's replacement, a one-metre lead.

The 21-year-old bared his teeth and did just enough to hold off a fast-closing Greene to win by the thickness of his vest, sparking wild celebrations of disbelief in the British camp.

None of the British quartet made Sunday's men's 100 metres final, while Gatlin, Greene and Crawford finished first, third and fourth respectively.

"It is a dream come true. We had amazing faith in each other," said Gardner.