Olympic 100m:Usain Bolt remains the fastest man on the planet after setting the second quickest time ever, an Olympic record of 9.63 seconds, to beat fellow Jamaican Yohan Blake into second and American Justin Gatlin into third. Bolt's 9.58 seconds in winning the 2009 world championship title is the only quicker time in history.
Tonight's brilliant display as he made up a massive early deficit proved he had completely recovered from the hamstring problems that had given a sliver of hope to his rivals.
World champion Blake posted a personal best of 9.75 seconds and 2004 champion Gatlin beat his with a 9.79, as the first seven home broke 10 seconds. Asafa Powell was the only one left out as he pulled up injured.
Tyson Gay finished fourth in a season's best 9.80 seconds with fellow American Ryan Bailey fifth in an equal PB of 9.88, buy it was all about Bolt who said repeatedly that he needed back-to-back titles to cement his place among the sport greats.
Carl Lewis is the only other man to win two Olympic 100m titles and the American's second gold came only after Ben Johnson was disqualified for doping.
Bolt, who was disqualified from last year's world championship final for a false start, was slow out of the block and trailed Blake, who beat him in the Jamaican trials, and Gatlin, back in the mix after serving a doping ban.
However, his massive stride reeled them in and he roared through the line, barely easing his speed as he tore round the bend to soak up the adulation of the delirious crowd.
"When I went out in the first run, I felt 'I can do this,' Bolt told the BBC in reference to his opening heat on Saturday. "I was slightly worried about my start, I didn't want to false start again. So I think I sat in the blocks a little bit, I don't think it was the best reaction in the world, but I executed and that was the key.
"Remember I told you my coach said 'stop worrying about your start', the best of your race is at the end, that's where you rule. So I stopped worrying about the start and I executed, so it worked."
Bolt will now bid to complete an unprecedented double-double by retaining his 200 metres title and will also seek a sixth sprint gold in the 4x100 metres relay.
"Usain knows what it takes, he is a world beater and he is the fastest man in the world," said Blake. "But I got a medal in my first Olympic games and a lot of that is down to Usain and our coach."
Jamaican Shelly-Ann Fraser-Pryce also retained her women's title to give her country a flying start in their sprint showdown with the United States.