Former cyclist Lance Armstrong has pulled out of a scheduled appearance in Dublin tomorrow for legal reasons.
The seven time winner of the Tour de France, who was stripped of his titles in 2012 after a protracted doping scandal, was due to appear at the One Zero conference.
However, he has now said he will not be appearing due to an upcoming US Federal court case against him, which is being brought against him on behalf of the US Postal Service.
Conference organisers say they had received assurances that the case would not be an issue and Mr Armstrong had been contracted to speak at the event since August.
Mr Armstrong was expected to participate in an interview session at the widely-publicised conference, followed by a question and answer session with the audience.
In a statement Rob Hartnett, one of the founders of the event, said: "We are extremely disappointed that Armstrong has withdrawn at the last minute from appearing at One Zero.
"He has let us down, he has let his fans down and his has let down those that wanted to hear him openly discuss his past and the future of sport".
Tickets for the one-day event at Dublin's RDS were on sale from €175 to €775.