Lance Armstrong is likely to be stripped of his seven Tour de France titles and banned from cycling for life after dropping his fight against doping charges.
The news means Armstrong is likely to lose all of the Tour de France titles he won between 1999 and 2005.
The 40-year-old Armstrong today saying "enough is enough" in his bid to clear his name, after a US federal court last month dismissed his lawsuit against the United States Anti-Doping Agency (USADA).
"There comes a point in every man's life when he has to say, 'enough is enough'. For me, that time is now," Armstrong said in the statement.
"I had hoped that a federal court would stop USADA's charade.
"Although the court was sympathetic to my concerns and recognised the many improprieties and deficiencies in USADA's motives, its conduct, and its process, the court ultimately decided that it could not intervene."
Armstrong has always maintained his innocence but his decision not to fight the USADA's charges means he will almost certainly be stripped of the seven consecutive Tour de France titles won after returning to the sport from successful treatment for testicular cancer.
"If I thought for one moment that by participating in USADA's process, I could confront these allegations in a fair setting and - once and for all - put these charges to rest, I would jump at the chance.
"But I refuse to participate in a process that is so one-sided and unfair."
Despite paving the way for the USADA to step up their investigation into charges he used performance-enhancing drugs, Armstrong said the agency lacked the authority to strip him of his titles.
"USADA cannot assert control of a professional international sport and attempt to strip my seven Tour de France titles," Armstrong said.
"I know who won those seven Tours, my team-mates know who won those seven Tours, and everyone I competed against knows who won those seven Tours."
But USADA chief executive Travis Tygart has reportedly said the agency does have the authority to void Armstrong's victories.
Tygart told the Associated Press the Armstrong case is a "heartbreaking example of a win-at-all costs approach to sports".
The USADA previously claimed it has witnesses who allege that Armstrong and five former cycling team associates - including Italian doctor Michele Ferrari and team manager Johan Bruyneel - engaged in a doping conspiracy between 1998 and 2011.
And Dutch newspaper De Telegraaf that George Hincapie and fellow American Tour de France riders Dave Zabriskie, Christian Vande Velde and Levi Leipheimer all testified against Armstrong.
Should Armstrong lose his titles then retired German rider Jan Ullrich - who twice finished as runner-up to the Texan - fellow German Andreas Kloden, Swiss rider Alex Zulle, Spaniard Joseba Beloki and Italian Ivan Basso could all benefit.
All five riders finished second to Armstrong during his seven-year reign of dominance, although Ullrich and Basso have also served doping suspensions during their careers.
Armstrong's lawyers contend he has "passed every drug test ever administered to him in his career - a total of 500 to 600 tests... more drug tests than any athlete in history".
They say the International Cycling Union has proper jurisdiction in the case.
- Lance Armstrong
- Tour de France