"All I've been hearing is doping, doping, doping, all the questions have been about doping.
Olympic and world sprint champion Usain Bolt has been saddened by the focus on doping in the run-up to the world championships but said it was up to all clean athletes, not just him, to save the sport.
The governing International Association of Athletics Federations (IAAF) has spent the three weeks leading up to its showpiece event defending its record on doping after a string of embarrassing leaks. [ID:nL3N10D00K]
"It's really taken centre stage," the Jamaican told a news conference on Thursday. "All I've been hearing is doping, doping, doping, all the questions have been about doping.
"It's sad that it's been at the forefront for the world championships and not the competition.
"There's nothing I can do about it though."
In the midst of the doping crisis, the sprint showdown between Bolt, who has never failed a drugs test, and in-form American Justin Gatlin, who has served two suspensions for using banned substances, has been billed as a battle for the soul of the sport.
Gatlin's second positive test, in 2006, would normally have earned him a lifetime ban but after he agreed to co-operate with the anti-doping authorities that was cut to eight, and then four years.
Bolt, who turns 29 on Friday, said he had no problem running against Gatlin if the rules say the former Olympic and world champion is eligible, and rejected the idea that, as the sport's biggest star, it was his responsibility to save it.
"Initially I'm running for myself, that's what I do," he said.
"People are saying I need to win for the sport but there's a lot of other athletes out there running clean, and who have run clean throughout their whole careers," he added.
"I can't do it by myself, it's a responsibility of all the athletes to take it upon themselves to save the sport and go forwards without drug cheats.
"It's not just on me but all the other athletes."
It was at the Bird's Nest stadium in Beijing that Bolt first established himself as the sport's biggest star, winning both sprint titles and a relay gold, all in world record times, at the 2008 Olympics.
Seven years of almost complete dominance of the sprint titles at major championships have followed, the only blot on his resume being the 100 metres final in Daegu in 2011 when Bolt was disqualified for a false start.
Happy with his form for the Aug. 22-30 championships despite having raced less than he would have liked this year because of a problem with his joints, he said the smile of his coach Glen Mills at recent training sessions has been reassuring.
Bolt, who set 100m (9.58) and 200m (19.19) world records at the 2009 world championships in Berlin, said he was ready to extend his reign as the world's fastest man.
"When I'm at a championships, everything comes together," he said. "I'm happy, I'm ready to go."