Some 4.3m people in the United States watched part one of the Armstrong interview on Winfrey's OWN network. In addition, 600,000 people watched the live steam on Oprah.com. No viewing figures are yet available for the Discovery Channel's coverage in the UK.
"I'd love the opportunity to compete, but that isn't why I'm doing this."
For the second night running, the interview with Winfrey, 58, was broadcast on prime time television on her OWN network in America, and was streamed worldwide through her website.
first part of the interview
the American ended years of denials by admitting using performance-enhancing drugs during all seven of his Tour de France wins.
During part two, in which he fought back tears as he discussed the impact on his family, he revealed:
he wants the life ban in sports lifted but accepts that is unlikely
he feels "disgraced, humbled and ashamed" by his actions
his "most humbling moment" was being asked to step aside by cancer charity Livestrong
the moment he confessed to his son and said: "don't defend me anymore"
his actions had left his mother a "wreck"
his sponsors leaving him was a "$75m day"
Of his desire to return to sport, Armstrong said he wasn't looking to take part in the Tour de France again, but added: "If you're asking me if I want to compete again, the answer is 'hell yeah, I'm a competitor'. It's what I've done all my life. I want to race, want to toe the line.
"There are lots of things I can't do because of the ban. If there is a window of opportunity would I like to run the Chicago Marathon when I'm 50? Yes.
"When you see the punishment... I got a death penalty meaning I can't compete. I'm not saying that is unfair but it is different."
The day sponsors quit
On October 17 last year, six days after the report labelling him a "serial cheat" was published, seven sponsors dropped Armstrong. These included key accounts such as with sportswear giant Nike, cycle maker Trek and Budweiser brewer Anheuser-Busch. At the time it was estimated to have cost the cyclist $30m but he told Winfrey it was a "$75m day".
Armstrong said he "selfishly" wanted his life ban to be lifted. "Realistically, I don't think that will happen and I've got to live with that," he added.
Armstrong started the second part of the interview, broadcast in the UK on the Discovery Channel, by telling the US chat show host he felt "disgraced, humbled and ashamed" at his use of performance-enhancing drugs.
"Do I have remorse? Absolutely. Will it grow? Absolutely," he said. "This is the first step and these are my actions. I am paying the price but I deserve it.
"The ultimate crime is the betrayal of these people who support me and believed in me and they got lied to."
He said what he had done hit home when his cancer charity Livestrong asked him to step aside last year. "That was the most humbling moment," he said.
Usada said he was a "serial cheat" who had led "the most sophisticated, professionalised and successful doping programme sport has ever seen".
He said: "Nike called and said that they're out. Then the calls started coming.
"A couple of days: everybody out."
Usada's case against Armstrong
Armstrong's USPS/Discovery Channel pro cycling team operated the "most sophisticated, professional and successful doping programme that sport has ever seen".
The American was "engaged in serial cheating" and his career at the team was fuelled from start to finish by doping.
More than a dozen former team-mates, friends and former team employees confirmed a fraudulent course of conduct.
Armstrong acted with the help of a small army of enablers, including doping doctors, drug smugglers and others within and outside the sport and his team.
He had ultimate control over not only his own personal drug use but over the doping culture of the team.
Team staff were good at predicting when testers would turn up and seemed to have inside information.
Armstrong described the period in which his sponsors dropped him as a" $75m dollar day". "All gone. Probably never coming back," he said. "I've lost all future income."
Outlining the build-up to Livestrong's decision, he added: "The story was getting out of control which was my worst nightmare. I had this place in my mind they would all leave. The one I didn't think would leave was the foundation.
"The foundation is like my sixth child and to make that decision and step aside was big.
"I was aware of the pressure and it was the best thing for the organisation but it hurt like hell."
Armstrong fought back tears as he described the impact of his actions on his five children.
"They know a lot," he said. "They hear it in the hallways. Their schools, their classmates have been very supportive. Where you lose control with your kids is when they go out of that space: Instagram, Twitter, Facebook, in the feedback columns.
"When this all really started, I saw my son defending me, and saying 'that's not true'.
"That's when I knew I had to tell him. And he'd never asked me. He'd never said 'dad, is this true?' He'd trusted me.
"I said 'don't defend me anymore, don't'. He has been remarkably calm and mature about it."
Armstrong said his mother had been left a "wreck" by what had happened but "she is a tough lady and has got through every other moment".
Despite the fallout from his drugs use, Armstrong said it was not the worst period of his life and pointed to his cancer battle.
"I've been to a dark place that was not of my doing where I didn't know if I would live," he said.
"You can't compare this to an advanced diagnosis. That sets the bar. It is close but I'm an optimist and I like to look forward - this has caused me to look back and I don't like that.
"When I was diagnosed I was better and smarter after that and then lost my way.
"It is easy to sit here and say I feel better but I can't lose my way again.
"Only I can control it and I'm in no position to make promises but that is the biggest challenge for the rest of my life - not to slip up again and not lose sight of what I have to do. I had it but things got too crazy. Epic challenge."
In the first part of the interview Armstrong told the chat show host he was sorry for his "big lie". He admitted that at the time he viewed his actions as levelling the playing field rather than cheating.
He said he would now co-operate with official inquiries into doping.
In the aftermath of the Usada report the Texan opted not to contest the allegations. He had always strongly denied doping, but that all changed within seconds of his first appearance on Winfrey's show.
Oprah interview day 1: Lance Armstrong admits doping to win cycling titles
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