World Championships: Usain Bolt saddened by doping focus

Usain Bolt is "sad" the focus is on doping ahead of the World Championships in Beijing but says he cannot save the sport's reputation on his own.

Bolt, who has never failed a drugs test, will race against American Justin Gatlin, who has served two suspensions for using banned substances.

Jamaican sprinter Bolt, 28, is seeking to retain his 100m and 200m titles.

"It's sad. People are saying I need to win for the sport, but I can't do it by myself," Bolt said.

"It's a responsibility of all the athletes to take it upon themselves to save the sport and go forwards without drug cheats."

The showdown between Bolt and Gatlin, who has the quickest times of the year over 100m and 200m, 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 that was cut to eight and then four years on appeal after he agreed to co-operate with the anti-doping authorities.

The build-up to the championships, which begin on Saturday, have been overshadowed by accusations of widespread doping in the sport.

The International Association of Athletics Federations (IAAF) has defended its record on doping.

"All I've been hearing is doping, doping, doping," said Bolt. "All the questions have been about doping."

The men's 100m final takes place on Sunday.

Gatlin is the favourite ahead of Bolt, who won his first Olympic title inside the Bird's Nest stadium seven years ago.