It was reported yesterday that the disgraced cyclist had confessed to Winfrey that he had used performance-enhancing drugs while competing in the Tour de France.
While she admitted that Armstrong "did not come clean in the manner that I expected," she and her team were nevertheless "mesmerized and riveted" by some of the answers he gave.
Winfrey said the interview lasted two-and-a-half hours and that she had come prepared with 112 questions.
"I asked most of those questions, or at least as many of those questions that I could, but I feel that he answered the questions in a way that he was ready," she said, adding: "The most important questions and answers that people around the world had been waiting to hear were certainly answered."
Winfrey also remarked how Armstrong came across during the interview.
"I felt that he was thoughtful. I thought that he was serious," she said. "I thought that he certainly had prepared himself for this moment. I would say that he met the moment, and at the end of it, we both were pretty exhausted. And I would say satisfied."
Winfrey later noted that her time with Armstrong was, at times, emotional.
"But emotional doesn't begin to describe the intensity or the difficulty that I think that he experienced in talking about some of these things," she said. "He brought it, he really did."
The interview will air over two nights on the OWN network starting this Thursday.
(Originally published on Jan. 15, 2012 at 7:14 a.m. PST)