Triple Olympic champion Usain Bolt said he was "made to inspire" and that his world-beating exploits on the track were down to natural talent and not performance-enhancing drugs.
The credibility of men's sprinting has been thrown into question in recent weeks by the news that American Tyson Gay and Bolt's Jamaican team-mate and friend, Asafa Powell, have tested positive for banned substances.
But, ahead of his eagerly-awaited appearance at the Anniversary Games in London's Olympic Stadium today, Bolt insisted he was 100pc clean and that the only advantage he had over his rivals was his gift for running fast.
"If you've been following me since 2002, you would know I've been doing phenomenal things since I was 15," he said. "I was the youngest person to win the world juniors. I ran the world youth record at 17. I've broken every record there is, in every event I've ever done. For me, I've proven myself since I was 15. I'm just living out my dream now.
"I was made to inspire people and made to run. I was given a gift and that's what I do. I know I'm clean, so I'm just going to continue running and using my talent."
Bolt, who takes on a top-class 100m field this evening, that includes fast-improving Briton James Dasaolu, faced a barrage of doping questions when he appeared before the media and admitted that the negative publicity swirling around the sport had "set us back a bit."
The fingers were pointing at Jamaica again when it was announced that an unnamed Jamaican international footballer had tested positive for a banned substance following a match against Honduras on June 11.
The Caribbean island, where sprinting is the national sport, is still coming to terms with the news that Powell, the former 100m world record holder, and team-mate Sherone Simpson are facing drug bans after testing positive for the stimulant Oxilofrine at last month's Jamaican trials.
Two-time Olympic 200m champion Veronica Campbell-Brown has already been provisionally suspended after a positive drug test in May.
"I know it must be hard," said Bolt.
"As Jamaicans, we're very proud of our athletes, because we brought glory to the country, so it's kind of rough. Hopefully, this will work out. I just have to continue working hard and bring glory to my country.
"Definitely, it's going to set us back a little bit, but I can't really focus on this. I'm just trying to work hard and run fast and, hopefully, help people move on from what's happened."
Powell and Simpson have blamed their failed drug tests on a new range of nutritional supplements they had recently been given by their physical trainer. Bolt declined to comment on the specifics of their cases until more details are known, but said athletes needed to be scrupulously careful about what they consumed to ensure they were not ingesting banned substances.
He said: "I have vitamins that I take. Every athlete takes vitamins. But I don't really take supplements. You have to be careful as an athlete, but I'm not worried because I have a great team around me.
"I make sure I'm careful as well. You have to trust the people around you because they check everything you're taking to make sure it's not on the banned list. They read the fine print."
Bolt admitted he was surprised by the latest revelations and that he had texted Powell when he heard the news.
"I told him I was sorry to hear what's going on and I told him to stay strong and stay focused and hopefully everything will work out," said Bolt.
The drug scandal has cast a shadow over the sport just when it was supposed to be celebrating the anniversary of arguably the greatest nine days of championship athletics at last year's Olympics, though three days of world-class action in the Olympic Stadium should help to restore some faith.
The entire meeting is a sell-out, with tickets for today's and tomorrow's Diamond League sessions being snapped up in just 75 minutes. The men's 100m closes tonight's programme and, after returning to the training track last month to sharpen up his speed, Bolt is promising to put on a show.
It is the least he can do after the Chancellor, George Osborne, took the generous step of making the meeting tax-free for overseas athletes to persuade Bolt to compete.
"I've been working hard," said Bolt. "I've gone through two and a half weeks of just solid training – everything is there that I needed to work on. I'm confident I'm ready to run and run fast."
With a season's best of 9.94, Bolt finds himself in the unusual position of being only the third fastest man on the start-line based on recent performances, with fellow Jamaican Nesta Carter having clocked 9.87 and Dasaolu running 9.91 in Birmingham 13 days ago to become the second fastest Briton in history behind Linford Christie.
Dasaolu (25) has yet to compete against Bolt and is relishing the prospect of testing himself against the world's fastest man.
"I know I'm going to have to run quicker if I'm going to challenge him and the rest of the guys," he said. "Of course, I've broken that sub-10 barrier so I feel I belong and it will give me confidence. But he's the quickest man to ever live, so it's going to be hard to follow in his footsteps." (© Daily Telegraph, London)
London Anniversary Games, Live BBC2, 7.30/BBC1, 8.30