Allyson Felix, the 2012 Olympics 200m sprint champion, believes that it will be a dark day if the all-conquering Jamaican track team are found to be lax in their anti-doping practices.

The 27-year-old American, who will flag off the Nike We Run SG at the Formula One Pit Building on Sunday morning, said: "Any time when you have anyone who has been caught doping, it is unfortunate and it sets our sport back."

Already, Jamaican athletes Asafa Powell, Veronica Campbell-Brown and Sherone Simpson all recently failed drug tests. A verdict on World Anti-Doping Agency's (Wada) audit on the island's anti-doping credibility is expected in the middle of this month.

Felix added: "It is a difficult process (to catch drug cheats). We really have to rely on the authorities that are there - Usada (US Anti-Doping Agency) in the case of America and overseas, Wada.

"We have to trust that they are doing all that they can to catch people. And seeing people get caught is saying that we are on the right path."