British sprinter Dwain Chambers - ap

British sprinter Dwain Chambers is surprised that so many athlete still dabble with performance enhancing drugs, after so many have been caught in the past few years.

Chambers was himself caught in 2003 after an out of competition test returned a result for banned substances, which saw the athlete suspended for two years. But, claiming to having learned his lesson, the brit says he hoped others would have learned as well.

"I had hoped things would change," Chambers told British newspaper The Telegraph (telegraph.co.uk).

"I have definitely learned my lesson, and I hoped a lot more athletes would too."

Ahead of the Daegu World Championships, where Chambers will compete, both Jamaican Steve Mullings and American Mike Rodgers have returned positive results for banned substances and will miss the event. Both athletes are expected to present their cases in front of their local regulatory bodies.

The British athlete, in the same breath, also welcomed mandatory blood tests for all athletes, an unprecedented step announced by the IAAF earlier this month.

Steve Mullings

"I can only concentrate on myself as a clean athlete but I welcome the mandatory blood tests (introduced at these championships) which level the playing field. I would also welcome more frequent and rigorous testing in championships and in the off-season."

Banned for life from competing at the Olympic Games, which will be held in his home country next year, this week's World Championships will be the biggest stage left for the athlete to compete on and perhaps at 33 years old, his last hurrah.

While the man who unveiled his 'Project Bolt' plan at the last World Champs in Beijing, where he finished in 6th place, believes the reigning Champion Usain Bolt could be beaten this year, he is convinced the sprinter remains the man to beat.

"Usain has shown this season that he is a human being," he said. "This guy has been dominant in ways that were unimaginable to us as athletes, but the fact he has not been on top form does not put any doubts in my mind. He's still the No 1 contender."