Blake, who had inherited Bolt's world title a year earlier when the defending champion (pictured top, alongside Justin Gatlin) was disqualified for false-starting, finished with silver and Justin Gatlin, back in the sport after serving a four-year doping ban, took bronze in a race in which seven of the eight finalists ran under 10 seconds, making it the fastest Olympic 100m final ever.

The Olympic Stadium, packed with 80,000 spectators, was a cauldron of anticipation as the runners lined up, and the question being asked was whether Bolt would be able to re-establish himself as the number one following his demoralising defeats over both 100m and 200m at the Jamaican trials.

There was less clowning from him beforehand than he had indulged in a year earlier at the Daegu World Championships; he only allowed himself the crowd-pleasing luxury of his trademark "lightning bolt" stance after he had achieved his first goal with a time only bettered by his own world record effort of 9.58 set in winning the 2009 world title.

Blake equalled his personal best of 9.75 with Gatlin also setting a new personal best of 9.79, beating his United States team-mate Tyson Gay – who ended the night in tears – by 0.01.

Usain Bolt powers away from his rivals to retain his Olympic 100 metres crown

Asked if he now considered he had achieved his stated goal of becoming a legend, he responded: "That's the first step for me.

"If I have won the 200 metres title also that's when I will consider myself a legend.

"So this is just a step in the door and I'm looking forward to the 200."

However, he said that retaining his title meant more to him because he had arrived at the Games, in his own phrase, only "95 per cent fit".

"Yeah," he said, "it really means a lot because a lot of people doubted me, a lot of people were saying I wasn't going to win, that I didn't look good.

"There was a lot of talk.

"So it was great to come out and show that I was still the number one, that I'm the still the best.

"I was slightly nervous before tonight.

The dominant margin of Usain Bolt's victory is clear as he crosses the line in Olympic record time

"But after that cheer I got when I came into the stadium the jitters went away.

"My coach explained to me after the trials that I had to stop worrying about my start and concentrate on the end of the race, because that's where I rule.

"It wasn't the perfect start – I think I sat in the blocks.

"But for me it was then about just executing.

"When I got to 50 metres and looked round I knew I was going to win, so I just ran, pretty much.

"I almost did that thing I did in Beijing."

He added: "It's definitely harder defending a title than winning it in the first place.

"When you get to the top of something you can lose sight of things, of what is going on; people are telling you that you are great.

"At the trials, Yohan Blake beat me twice, and that opened my eyes.

"I thought 'This is the Olympics – are you ready for them?'

"After the semi-final I was really confident because my legs felt good.

"I didn't really remember I was racing against the clock until maybe 25, 30 metres to go.

"I looked across at the clock but it was too late.

"But it was the second fastest time in the world so I'm happy."

America's Sanya Richards-Ross takes the honours in the women's 400 metres

Elsewhere, Britain's reigning Olympic 400m champion Christine Ohuruogu had to settle for silver in the race which took place less than a mile from her family home.

The Briton moved from seventh to second in the final 80 metres, but could not quite get past the world champion, Sanya Richards-Ross of the US, who won in 49.55.

Ohuruogu clocked a season's best time of 49.70 to claim silver with DeeDee Trotter of the US taking bronze.

Ohuruogu lay back on the track and stayed there for more than a minute afterwards.

"I was stunned," she said.

"I was heartbroken actually.

"To lose your title like that was tough.

"Sanya is a worthy competitor, though.

Distraught runner-up Christine Ohuruogu dwells on losing her Olympic 400 metres crown

"I tightened up and felt my shoulders lifting; I thought I still had some time but the line came too soon.

"I always came here for one thing and one thing only, and that was continuing my reign so I am disappointed.

"It's great that everyone has got behind the Games and it's them who have made this so special – it means so much to us."

Meanwhile, Yamilé Aldama, tipped as a possible gold medal contender, finished fifth in the women's triple jump final that was won by Olga Rypakova, whose best was 14.98 metres.

Rypakova thus won the first track and field gold for Kazakhstan since her namesake, Olga Shishigina, won the 100m hurdles at the 2000 Sydney Games.

Kenya's Ezekiel Kemboi (far left) takes an unusual route to gold in the men's 3,000 metres steeplechase

The men's 3,000m steeplechase title went, unsurprisingly, to Kenya, although the manner of Ezekiel Kemboi's finishing flourish was surprising as, with victory apparently assured, he veered out all the way to lane eight before crossing the line in 8min 18.56sec.

It nearly set up what would have been one of the great unlikely Olympic victories for France's Mahiedine Mekhissi-Benabbad, who finished one second behind via the more conventional route of lane one.

"I am practising for the marathon," Kemboi observed laconically afterwards.

Hungary's Krisztián Pars finally struck gold in the hammer after years of bronze and silver medals with a winning effort of 80.59 metres.

Man arrested after bottle thrown on to track moments before start of 100 metres final

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