The Sunday Times is suing Lance Armstrong for up to £1m after he was given a life ban and stripped of his seven Tour de France titles for doping.
Armstrong, 41, was paid £300,000 to settle a libel case in 2004 after the newspaper alleged he had cheated.
The US Anti-Doping Agency found he had led the "most sophisticated" drug-taking programme in sport.
The newspaper is demanding the return of the £300,000 settlement payment along with interest and legal costs.
Its letter to Armstrong's lawyers read: "It is clear that the proceedings were baseless and fraudulent. Your representations that you had never taken performance-enhancing drugs were deliberately false."
David Walsh, the chief sports writer of the Sunday Times, first raised questions about Armstrong in 1999, when he won the Tour de France for the first time.
In 2004, the newspaper published an article saying it was right for questions about Armstrong's performance to be both "posed an answered".
The American cyclist's lawyers issued a writ and it was later ruled that the meaning of the article was that Armstrong was "a fraud, a cheat and a liar".
The Sunday Times settled with him in June 2006.
The American has always denied taking performance-enhancing drugs but chose not to fight Usada's charges against him.