Stuart O'Grady accepts all of his great cycling career achievements will be clouded after he confessed to doping in the lead-up to the 1998 Tour de France.
"You win Olympics, Paris-Roubaix and now all of that is going to be tainted by this action and I wish it could be changed but it can't," said O'Grady.
"That's the hardest thing to swallow out of all this - it was such a long time ago and one very bad judgment is going to taint a lot of things and people will have a lot of questions."
O'Grady admitted on Thursday to using the banned blood booster erythropoietin (EPO) in preparation for the infamous 1998 Tour.
His confession came after he was named, with other riders from that race, in a French parliamentary inquiry into the use of drugs in the sport.
That development emerged a day after he surprised by announcing his retirement after riding a record-equalling 17th Tour, despite recently signing a new deal for another season with Australian-owned team Orica GreenEDGE.
O'Grady insisted his doping in 1998 was a one-off bad decision.
"Leading into the Tour, I made a decision, I sourced it (EPO) myself, there was no one else involved, it didn't involve the team in any way," O'Grady told News Limited.
"I just had to drive over the border and buy it at any pharmacy.
"The hardest part of all this is I did it for two weeks before the Tour de France. I used extremely cautious amounts because I'd heard a lot of horror stories and did the absolute minimum of what I hoped would get me through.
"When the Festina Affair happened, I smashed it, got rid of it and that was the last I ever touched it."
Cycling Australia chief executive Graham Fredericks agreed O'Grady's decorated career would remain clouded.
"Stuart has been one of Australia's most enduring road riders who appears to have made a poor decision which will regrettably now have an impact on the legacy of his career," Fredericks said in a statement on Thursday.
He added the late 1990s was a "dark period" in cycling's international history as riders transitioned from strict anti-doping regimes in Australia to a more liberal approach in Europe.
"In the years since this incident, significant measures have been implemented to eliminate the scourge of drugs from the professional peloton. The sport is in a cleaner position now than it has ever been," said Fredericks.
Orica-GreenEDGE team manager Shayne Bannan on Thursday stressed that the two-year-old team competed "100 per cent clean", while also backing O'Grady's integrity.
"The team would also like to express its support in Stuart as a person and as an advocate for a clean sport," Bannan said.
"Like the majority of the riders in his generation, he was also exposed to the issues and wrongdoings of the sport and made some wrong choices in that environment.
"[But] we believe that certain mistakes in the past shouldn't be allowed to tarnish his entire career and his integrity as a person."
The French government inquiry accused 18 riders of having traces of EPO in their tests and said another 12, including O'Grady, had "suspicious" samples.
The tests were initially taken during the 1998 Tour and re-tested for EPO in 2004, with the inquiry gaining access to the controversial findings.
There was no test available in 1998 for EPO, the blood booster that became notorious in cycling over the past two decades as a favoured drug for cheats.
None of the riders named in the report is likely to face official sanctions.
The government inquiry was going to release its controversial findings during this month's Tour, but delayed until Wednesday after lobbying from the sport.
O'Grady was the only Australian named in the list of 30 riders.
He was among four Australians who rode in the 1998 Tour, which will forever be remembered as a landmark in the sport's tarnished doping history.
The race was dominated by the Festina Affair, with the French Festina team forced to leave the Tour after one of their support staff was caught with a large supply of doping products in his car.
The Festina Tour team that year included Australian Neil Stephens, who has always denied intentionally taking banned substances.
Robbie McEwen, who won 12 Tour stages, and Pat Jonker were the other Australians on that tour.
O'Grady was the last of the quartet to retire from competition.
Among the riders who were listed as returning positive EPO tests were 1998 Tour champion Marco Pantani and runner-up Jan Ullrich.
Pantani, who died in 2004, and Ullrich were dogged by doping controversies following the '98 Tour.