Four years of effort, exertion and preparation came down to a matter of seconds. 9.63 of them, to be precise.

If there were any serious doubts about Usain Bolt's right to be recognised as the greatest sprinter the world has seen, they were blown away emphatically on Sunday as the Jamaican retained his Olympic 100m crown.

The hottest ticket of the London Games -- seats for Sunday's final were reportedly changing hands on the black market for several thousand pounds -- had been billed as potentially the fastest race in history.

For once the hype was justified as a field containing the four fastest men on the planet lined up, with Bolt joined by compatriots Yohan Blake and Asafa Powell, and Americans Tyson Gay and Justin Gatlin.

Jamaica's Usain Bolt (L) wins the men's 100m final at the athletics event during the London 2012 Olympic Games in London.

As the race was announced on the giant screens, a wave of noise surged round the capacity crowd and camera flashes flickered in every block. But it was nothing compared to the 9.63 seconds ahead.

"The time has come," the crowd were told, to a giant roar.

"80,000 of you; eight men; nine seconds; the men's 100 metres final!"

While the other competitors stripped off and tried to relax, Gatlin walked 99 metres of the way, visualising his race until the final last step.

As the camera panned along the start line, it was show time.

Jamaica's Usain Bolt gives a thumbs-up as he celebrates winning the men's 100m final at the athletics event during the London 2012 Olympic Games in London.

Trinidad's Richard Thompson did a little dance, while Powell gave a mean stare into a TV camera. Gay breathed deeply and raised his right arm aloft. Blake drew himself up to his full height then made some scary monster hands, referencing his adopted moniker of "The Beast."

Gatlin, the 2004 Olympic champion who was later banned for doping, marched up to the camera and back again, before a cheer rocketed around the stadium as Bolt was introduced.

The towering 25-year-old did some impromptu DJ moves and wiggled some running fingers at the camera. The young American Ryan Bailey turned and applauded the crowd, while Churandy Martina of the Netherlands pointed his finger.

They settled down into their blocks.

Three Americans, three Jamaicans, one Dutchman and a man from Trinidad and Tobago and less than 10 seconds to sort out which one would have his name written in gold in Olympic history.

Nervous tension gripped the stadium as the fans held their breath for the seemingly endless seconds on the blocks.

Jamaica's Usain Bolt celebrates winning the men's 100m final at the athletics event during the London 2012 Olympic Games in London.

The Olympic Stadium, designed with a temporary upper tier, has been criticised by some for being plain and featureless.

But a stadium filled with 80,000 people and nothing else but the fastest men on the planet makes for one hell of an atmosphere.

Then the quiet was shattered by a explosion of sound and light, with a deafening ring of cheers, shouts and screams.

Bolt, as ever, was not the fastest off the blocks and for a few seconds looked as though his title might have gone.

But he puffed out his cheeks, looked dead ahead, and by the time he had glanced a few times to his left to see his rivals disappearing behind him, he was dipping for the line and breaking his Olympic record, his eyes on the clock as he did so.

Dancing round the stadium in delight, the hero performed his trademark 'Lightning Bolt' pose, the iconic image for which he will always be remembered.

Four years after dazzling the world in Beijing, 'Lightning' had struck twice.