Seven-time Tour de France winner Lance Armstrong has announced his retirement from professional cycling at the age of 39.
'Today, I am announcing my retirement from professional cycling in order to devote myself full-time to my family, to the fight against cancer and to leading the foundation I established before I won my first Tour de France,' Armstrong said in a statement.
'My focus now is raising my five children, promoting the mission of (his foundation) Livestrong, and growing entrepreneurial ventures with our great corporate partners in the fight against cancer.'
Armstrong initially retired from cycling after the 2005 Tour de France, but returned to competition in 2009.
The American went on to finish third in the 2009 Tour de France and most recently placed 67th in the Tour Down Under in Australia last month.
There were hopes that Armstrong would race in the May 15-22 Tour of California, America's biggest cycling race after changes in the event's drug test programme opened the door for him to do so.
Armstrong is the subject of a federal investigation in the United States after allegations of doping levelled by disgraced former teammate Floyd Landis, who was stripped of his 2006 Tour de France title for using illegal substances.
But Armstrong, who was diagnosed with testicular cancer at the age of 25, has never tested positive for performance-enhancing drugs and has consistently denied allegations of doping.
International Cycling Union president Pat McQuaid dubbed Armstrong an 'icon' in the sport.
'His contribution to cycling has been enormous, from both the sporting point of view and his personality," said McQuaid.
'All sports need global icons and he has become a global icon for cycling. The sport of cycling has a lot to be thankful for because of Lance Armstrong.'