Here was a man renowned for never throwing in the towel — a man who once crashed on his way to winning at Luz Ardiden, a man who recovered from life-threatening cancer not only to live a healthy life but also to win cycling's hardest stage race seven times — finally saying, quite literally, that "enough is enough".
The US Anti-Doping Agency and the World Anti-Doping Agency claim that by stepping down, Armstrong has effectively conceded he won his record seven Tours by doping.
While caving in is not always an admission of guilt — just look at British Olympic sailor Ben Ainslie, who recently agreed to complete a penalty turn after being accused erroneously of malpractice by his main rivals during a race on the way to a record fourth gold medal — in Armstrong's case, it certainly does not look good.
In the eyes of his nation's doping agency, Armstrong has been named a doping cheat; instead of contesting the charges and clearing his name in a court of law, Armstrong has branded the "outlandish and heinous … pitiful charade" a "witch hunt" and has instead challenged USADA's legitimacy in the court of public opinion.
The whole thing stinks more of fish than a visit to Tokyo's famous Tsukiji Market.
In a bullish statement, Armstrong wheeled out his faltering defence of being the most tested athlete in the world, once again stressing the "zero physical evidence" held against him.
(It should be noted that over the past five years, USADA has busted around 50 athletes, including Marion Jones, who passed around 160 drugs tests in her career before being outed as a chronic doper.)
But while we, the public, aren't privy to the full range of evidence that would have been levelled against the Texan had the case gone to arbitration, Armstrong and his lawyers have certainly seen the full USADA dossier built up by Travis Tygart — and that seems reason alone to stand down.
The agency is said to be claiming that Armstrong used EPO, Coriticosteriods, Testosterone, Human Growth Hormone, blood transfusions and — to mask all the above — saline and plasma infusions. Armstrong is also said to have encouraged and facilitated doping by his team-mates at US Postal and Discovery. Around 10 former team-mates were prepared to come forward and testify.
Rather than face a rap sheet bigger than his own palmares, Armstrong has quite understandably caved in and chosen to sidestep the whole thing — even though that means having his titles taken away from him by USADA.
(Given that cycling is an Olympic sport that follows the World Anti-Doping Code, USADA does certainly have the jurisdiction to do this — although it remains to be seen how the UCI and the Tour organisers ASO react, especially given their supposed roles in the whole Lance fandango.)
"I know who won those seven Tours, my team-mates know who won those seven Tours, and everyone I competed against knows who won those seven Tours."
That's all very well, Lance, but we, the public, still don't know who won those races. One thing's for sure — from now on, journalists will have to think twice when describing Armstrong as a "seven-time Tour de France champion".
But if cycling is going to go and employ the same method that has declared in recent years Oscar Pereiro the winner of the 2006 Tour, Andy Schleck the 2010 Tour winner and Michele Scarponi the 2011 Giro d'Italia champion, then we're going to have to get used to Jan Ullrich — of all people — being described as a "four-time Tour winner".
No one in the cycling world will welcome with open arms handed-down titles to Ullrich, Alex Zuelle, Andreas Kloeden, Joseba Beloki and Ivan Basso.
Prize money — an estimated $5m — is to be repaid, but what about the 22 cuddly Credit Lyonnais lions that Armstrong picked up as a stage winner in all those years?
As for Johan Bruyneel, the man in charge of Armstrong's winning teams, will he ever actually be ordered to change the tag-line of his own personal website so that it doesn't boast "9X WINNING TOUR DE FRANCE SPORTS DIRECTOR"?
So many questions, so few answers.
Once again, the whole thing has become a complete and utter farce — and in the words of Eurosport commentator David Harmon, it's an "appallingly unsatisfactory situation" in which only two riders from the top five in Tours from 1999 to 2005 (that's to say, the Armstrong years) have never been linked to doping.
Rather than playing a futile game of hand-me-down, surely it would be a better signal to the sport to see those years completely vacated of a winner, creating a seven-year void that will serve in the future to remind cycling of its dark days.
But even then, when do you stop? What about the dubious results either side of Armstrong's years of dominance? Indeed, Armstrong made a comeback to the sport in 2009 and finished third in the Tour de France, denying Bradley Wiggins a place on the podium. Given what we know now — and USADA claims it holds evidence of blood doping even in those years — the audacity of Armstrong in returning to a sport that he had effectively duped for seven years seems unforgivable.
It's hard to know where to go from here. The French newspaper L'Express published an article on the morning after Armstrong give up the fight in which it published quotes from a French journalist expressing his opinion that 92% of winners of the Tour in the 40 years between 1967 and 2007 were dopers.
The journalist said that after in-depth investigations he had found that 35% of riders who competed during those years had at least once broken the rules or been linked to doping. "It gets worse the higher up you get in the classification," said Pierre Ballester. "It rises to 60% of riders who finished in the top 10, 75% who made the podium and 92% of winners."
Herein, of course, lies the problem. Cyclists have traditionally relied on cocktails of enhancements and none of them (nor their peers) have viewed themselves as cheats - just look at the great five-time champions Jacques Antequil and Eddy Merckx. There have been unwritten rules for too long. It's not the doping that matters, it's the getting caught.
And that is presumably why Armstrong is so bitter and angry. Evidence overwhelmingly suggests that he was doping at a time when all the top riders were at it. But while they were caught, he wasn't. Besides his infamous (allegedly backdated) prescription for corticoids in 1999, Armstrong was not snared while an active rider; what he was doing was not traceable back then and so, by some twisted logic, not illegal. In his eyes, it's unfair to be dredging up the past; after all, he was the best — in EVERY respect — in those seven Tours.
Armstrong's case has blown the lid on everything. But we must remember that the contents of Pandora's box spread far further than Armstrong's training and racing habits. The larger picture is about the system that allowed dopers to thrive for so long. A system which surely needed the complicity of people on every level of the sport — from riders to team managers, sponsors to cycling journalists, the race organisers to the people who run the sport.
Like a series of 24 — the chain of baddies just gets longer and goes deeper. Armstrong may be at the top of the food chain of cyclists during doping's darkest days, but the "witch hunt" is far from merely about him and now becomes a "which?" hunt. This is a complex, multi-layered issue in which Armstrong is but one character, albeit perhaps the most colourful.
The fact that daily donations to Armstrong's Livestrong charity were said to be up 2,500 per cent on Friday just goes to show how complicated and confusing this case has got.
On Twitter, support has come in for Armstrong. One fan said: "I still believe in you and you are an inspiration for many". "Still a hero in my eyes," said another. "This is the most ridiculous, unfounded travesty of justice ever. You won 7 Tours and no one can take that away," said one fan, clearly in denial. "I'm proud to support Lance. His accomplishments and fight against cancer are and will always be an inspiration," said yet another in a long and on-going list.
Axel Merckx, the son of Eddy and a rider whose career overlapped with that of Armstrong, described the American as "a friend, an inspiration for cancer and amazing athlete".
The thing is, Merckx is not wrong. Armstrong is undoubtably a friend to many, an inspiration to more and, clearly, an amazing athlete. But we can now probably add "doper", "cheat" and "liar" to that list.
It's a sign of the complexities of the sport and the Armstrong story that this latest bombshell will make no difference to his legacy to his hoards of fans worldwide. And given the amazing work he does for cancer sufferers and survivors, this is probably a good thing.