Attempting to explain his drug-tainted past, Armstrong sat down with Oprah Winfrey for his first interview since being stripped last year of his record seven Tour titles and banned from sport for life.

"I know the truth. The truth isn't what was out there, the truth isn't what I said... This story was so perfect for so long... you overcome the disease, you win the Tour de France seven times, you have a happy marriage, you have children. I mean, it's just this mythic, perfect story," Armstrong said.

"And it wasn't true."

Armstrong admitted using blood-boosting EPO, blood doping transfusions and testosterone or human growth hormone.

Hours before the kickoff, Armstrong saw another accolade withdrawn as the International Olympic Committee said it had asked him to return the cycling time-trial bronze medal he won in 2000.

The International Cycling Union last year upheld the US Anti-Doping Agency's ban of Armstrong, and the revocation of his cycling results from August 1998, but the IOC waited for three weeks to see if Armstrong planned an appeal.

While Winfrey confirmed on Tuesday reports that Armstrong had admitted using banned performance enhancers in their talk, little else was known of what he would reveal.

Speculation swirled as to whether he had implicated others -- notably members of the sport's world governing body -- amid allegations of complicity and cover-up.

The difficulty of untangling the doping web in cycling was again clear when the IOC's move recalled the 2000 Olympic time-trial medallists.

Abraham Olano of Spain, who was fourth, could inherit the bronze after finishing fourth in a race won by Armstrong's ex-US Post Service team-mate Viasheslav Ekimov, with Germany's Jan Ullrich taking silver.

Ekimov is now general manager of the Katusha cycling team that were dropped from the elite ProTeam list for this season because of their ambivalent stance on doping, and Ullrich eventually served a two-year ban for doping.

Some have speculated that Armstrong might attempt to rationalise doping as standard procedure in the years of his cycling career.

Certainly his admission, and his choice of the famously sympathetic Winfrey as confessor, are an about face after years of aggressive denials and often vitriolic attacks on those who doubted him.

"No one could have imagined only a few weeks ago that Lance Armstrong would make his confession publicly, that he would confess in public to having been doped," Tour de France director Christian Prudhomme told reporters in Paris.

"It's obviously something very important but I can't say more than that ... For us, Lance Armstrong is already in the past."

This week's exercise, however, is about the future, with Armstrong reportedly seeking a way back into sports and those in cycling wondering just who will be implicated in his revelations.