Disgraced cyclist Lance Armstrong has been forced to pull out of this weekend's Masters South Central Zone Swimming Championships in Texas.
The 41-year-old was due to make his competitive return to sport as a swimmer for the first time since his doping past was revealed.
While the event itself was thought not to be subject to the USA and World Anti-Doping Agency, it is understood that Armstrong pulled out due to pressure from the governing body of swimming.
The organisation claimed that Armstrong, who was given a lifetime ban from cycling, would be breaking the rules if he entered and a request for his admission not to be accepted would be made, according to Sky Sports News.
Armstrong was stripped of his record seven Tour de France titles.