American sprinter Christian Coleman is under investigation over concerns he may have missed three drugs tests, BBC Sport has been told.
If found guilty he would face an automatic one-year ban and would miss the World Championships in Qatar and the Olympic Games in Tokyo next year.
He is alleged to have had three possible failures under the 'whereabouts' system in the last year.
Coleman is understood to be contesting at least one of those cases.
Neither athletics' governing body the IAAF, the World Anti-Doping Agency, the US Anti-Doping Agency nor the Athletics Integrity Unit has commented on the situation, which was first reported in the Daily Mail.
BBC Sport has approached Coleman for comment.
Coleman won the US National Championships last month in a time of 9.99 seconds, having already set the fastest time of the year so far - 9.81secs in the Diamond League meeting at Stanford, California in June.