Usain Bolt tells reporters `` I 'm clean '' ahead of London Diamond League meeting . Powell and Gay failed drugs tests earlier this month . Tyson Gay and Tyson Gay both deny knowingly taking banned substances . A Caribbean international footballer fails a drugs test during a World Cup qualifier .
Usain Bolt tells reporters `` I 'm clean '' ahead of London Diamond League meeting . Tyson Gay and Asafa Powell failed drugs tests earlier this month . Gay and Powell both deny knowingly taking banned substances . A Jamaican international footballer fails a drugs test during a World Cup qualifier .