Armstrong on Thursday night dropped any further challenges to USADA's allegations that he took performance-enhancing drugs to win cycling's premier event from 1999-2005.
Armstrong says USADA doesn't have the authority to vacate his Tour titles. However, Tygart told The Associated Press that USADA can do it.
Tygart called the Armstrong case a "heartbreaking" example of a win-at-all costs approach to sports.
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