"I'm calm, I'm at ease and ready to speak candidly," Armstrong told The Associated Press, referring to his interview Monday with Oprah Winfrey.
In what's been billed as a "no holds barred" session, the cyclist is expected to reverse course after a decade of denials and apologize for doping, as well as offer a limited confession about his role at the head of a long-running scheme to dominate the Tour de France with the aid of performance-enhancing drugs.
Armstrong was stripped of all seven tour titles last year in the wake of a voluminous U.S. Anti-Doping Agency report that portrayed him as a ruthless competitor, willing to go to any lengths to win the prestigious race.
"The most sophisticated, professionalized and successful doping program that sport has ever seen," is how USADA chief executive Travis Tygart labeled the doping regimen allegedly carried out by the U.S. Postal Service team that Armstrong once led.
Yet if any of that was weighing on Armstrong's mind, he didn't show it early in the day.
Wearing a red jersey and black shorts, sunglasses and a white baseball cap pulled down to his eyes, he was training by himself and about a mile from his home when he talked to the AP. Armstrong ran for about an hour as his team of lawyers and advisers began arriving one-by-one at his house.
Leaning into a reporter's car on the shoulder of a busy Austin road, he also seemed unfazed by the international news crews gathering at the gates of his home. He cracked a few jokes about all the attention the interview with Winfrey had already drawn, then added, "But now I want to finish my run" and took off down the road.
The interview, which will take place at his home and broadcast Thursday on the Oprah Winfrey Network, will be Armstrong's first public response to the USADA report. A person with knowledge of the situation told the AP a day earlier that Armstrong will give a limited confession and apologize. He is not expected to provide a detailed account about his involvement, nor address in depth many of the specific allegations in the more than 1,000-page USADA report.
In a text to the AP on Saturday, Armstrong said: "I told her (Winfrey) to go wherever she wants, and I'll answer the questions directly, honestly and candidly. That's all I can say."
A confession would be a stunning reversal after years of public statements, interviews and court battles from Austin to Europe that Armstrong waged while zealously protecting his reputation.
After a federal investigation of the cyclist was dropped without charges being brought last year, USADA stepped in with an investigation of its own. The agency deposed nearly a dozen former teammates and accused Armstrong of masterminding a complex and brazen drug program that included steroids, blood boosters and a range of other performance-enhancers.