Justin Gatlin has fired coach Dennis Mitchell and distanced himself from allegations members of his team offered to supply performance-enhancing drugs.
United States Anti-Doping Agency (USADA) and the Athletics Integrity Unit have begun investigations into claims Gatlin's entourage could provide prescriptions in a false name and smuggle substances into America.
Mitchell and athletics agent Robert Wagner are at the centre of the accusations after reportedly telling undercover reporters from the Daily Telegraph they could supply and administer testosterone and human-growth hormone obtained from a doctor in Austria for $250,000.
USADA was keen to stress Gatlin was innocent until proven otherwise, and the 35-year-old has taken a stance by firing Mitchell and insisting he is a clean athlete.
"I am not using and have not used PED's," he posted on Instagram.
"I was shocked and surprised to learn that my coach would have anything to do with even the appearance of these current accusations. I fired him as soon as I found out about this.
"All legal options are on the table as I will not allow others to lie about me like this. I have no further comments as it is now a legal matter. They will next hear from my lawyer.
"Thank you all my supporters and well wishers."
When contacted by Omnisport, Wagner said he will be seeking legal advice.