PARIS, France (AFP) - Usain Bolt arrived at the last Olympics in Beijing with athletics at a low ebb, but he and the sport were transformed after the Jamaican left with then-world records in both the 100 and 200m.

The ebullient Bolt captured the public’s attention and went on to replicate his sprinting prowess at the 2009 World Championships, winning double gold, amazingly in new world records of 9.58 and 19.19 seconds respectively.

The world's fastest man became, and remains, athletics' hottest property, commanding huge appearance fees on the European circuit and earning enough that competing in London is prohibitively expensive thanks to the British taxman.

But in the run-in to the July 27-August 12 Olympic Games, a chink has appeared in Bolt’s armour, a shadow of doubt that has not been seen in almost four years.

It comes in the shape of training partner Yohan Blake, who stunned the world (but not all athletics pundits) by beating Bolt not just once, but twice, in the Jamaican Olympic trials.

The glass ceiling was well and truly broken. Bolt the unbeatable has become beatable, albeit for sprinters who regularly clock sub-9.90sec times.

"Bolt might be a little off at the moment, but I'm sure when the time of delivery comes around, he’ll be on top of his game," coach Glen Mills said of the 25-year-old after seeing Blake beat him in the 200m.

It was Bolt's first defeat in his favourite event in more than four years. He clocked 19.83sec to Blake's world leading 19.80, and immediately vowed to fight back.

"It is not like I was blown away," Bolt said, pinpointing his "sad" bend as the race's weak point.

"I've been working more on the 100 metres," he said. "I can't blame it on that, though. Just have to get my things together and get it done."

"It's all about work and just needing to get my things together and get it right. I got to get in the work and figure out what I did wrong."

"I have to work hard to get ready for the Olympics. I think I am a little bit weak but three more weeks should be good enough to get back into shape."

Born in Trelawny on August 21, 1986, Usain St Leo Bolt shot to prominence as a junior, winning 200m gold at the 2002 World Junior Championships at 15 years of age.

Standing 1.95 m (6ft 5in) tall and weighing in at 92kg, the prodigy progressed smoothly into senior ranks.

But the son of grocery-owning parents will have his work cut out to hold off the challenge of Blake and defend his Olympic titles, something he says would be necessary to make him a "legend" of the sport.

"I am the Olympic champion and I have to show the world I am the best," Bolt said. "I will always make a comeback."