ABC News has learned that former cyclist Lance Armstrong admitted in an interview with Oprah Winfrey Monday that he used performance-enhancing drugs during his seven Tour de France triumphs, finally acknowledging that he cheated to win after years of denials.

Meanwhile, very high-level sources tell ABC News that Armstrong is now talking with authorities about paying back some of the U.S. Postal Service money that was used to sponsor his cycling team.

The 41-year-old Armstrong is also apparently ready to name names, essentially giving up others involved in illegal doping in an effort to reduce the lifetime ban imposed by the U.S. Anti-Doping Agency.

Armstrong was not available for comment following the 2 1/2-hour interview at a hotel room in Austin, Texas, that will air Thursday on OWN at 9 p.m. while a Winfrey spokesperson said "We are not confirming specific details regarding the interview at this time."

Before the interview with Winfrey, Armstrong apologized to the Livestrong Foundation staff, which was orginially called the Lance Armstrong Foundation.

Armstrong gathered with about 100 staffers at their Austin, Texas, headquarters for a meeting that included social workers who deal directly with patients as part of the group's mission to support cancer victims.

Armstrong's "sincere and heartfelt apology" generated lots of tears, spokeswoman Katherine McLane said, adding that he "took responsibility" for the trouble he has caused the foundation.

However, at no time did Armstrong discuss steroid use or illegal blood transfusions that he has been accused of doing.

Until the Winfrey interview, Armstrong's story has never changed. In front of cameras, microphones, fans, sponsors, cancer survivors -- even under oath -- he has not only denied using performance-enhancing drugs, he has done so at times in an indignant, even threatening way.

It's believed that whatever Armstrong told Winfrey, he likely chose his words very carefully.

An out-and-out admission to steroid use could help him on the road to a comeback as a professional athlete since a lifetime ban has been currently imposed on him. Armstrong might also be able to stop his numerous sponsors from dropping him.

However, Armstrong could also open himself up to a flood of lawsuits if his confessions is too revealing. 

Last October, the U.S. Anti-Doping Agency said it had overwhelming evidence that Armstrong cheated during his career, accusations that were not disputed by either the World Anti-Doping Agency or the International Cycling Union, which was the group that negated his seven Tour de France championships.