LINZ - 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 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. –AFP