Lance Armstrong admits that his career was "one big lie".
The bicyclist, who claimed seven Tour de France victories, denied for years that he took performance-enhancing drugs.
Lance was formally stripped of his wins after being accused by anti-doping authorities of using forbidden substances.
During an interview that aired Thursday with Oprah Winfrey, Lance detailed the motivation behind his deceit.
"I don't know that I have a great answer. I will start now by saying this is too late... I view this situation as one big lie that I repeated a lot of times... I am a flawed character," Lance revealed to the American talk show icon.
"I didn't invent the [doping] culture, but I did nothing to stop the culture... and I am sorry for that."
Lance used EPO (erythropoietin) in the mid 1990s, but claims he was done with drugs by the time of his 1999 comeback.
When asked whether he was afraid of getting caught, if lying ever made him feel wrong or like he was cheating, Lance answered "no" to all three questions.
"I viewed it as very simple," he explained.
"You had things that were oxygen-boosting drugs, for lack of a better word, that were incredibly beneficial for endurance sports. And that's all you needed.
"My cocktail was only EPO ... not a lot ... transfusions and testosterone.
"[I was] an arrogant pr*ck."
The second part of TV interview special Oprah and Lance Armstrong: The Worldwide Exclusive will be broadcast Friday.
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