LINZ, AUSTRIA (AFP) - American sprinter Justin Gatlin says he is concentrating on himself and not thinking about recent doping scandals ahead of the world championships, which start next week in Moscow.

The 2004 Athens Olympic champion will be one of the main favourites for 100m gold in Russia as many of his main rivals will be missing.

Fellow American Tyson Gay and Jamaican Asafa Powell will be absent after failing drug tests, although the latter had not made the Jamaican team anyway.

The reigning world champion Yohan Blake, another Jamaican, is also out with injury.

It means Gatlin, 31, will start the competition as the main rival to twice triple Olympic gold medalist and world record holder Usain Bolt.

While he was himself twice banned for doping, Gatlin has refused to get involved in the current debate.

"I have to stay concentrated and get ready for the worlds," he said in an interview with Austrian press agency APA. "The show must go on. I think a lot of athletes think like that. Staying concentrated and winning for your country, that's what counts."

Gatlin's second failed dope test in 2006 saw him banned for four years but he has since made a comeback.

He and his American team-mates are training in Linz until August 5 before heading to Moscow, where the worlds start on August 10.