Armstrong is currently training in Tenerife
Lance Armstrong will attempt to win the Tour de France for an eighth time after confirming he will compete in the 2009 race.
Seven-times winner Armstrong, 37, who retired from cycling in 2005, but is to return to the sport next year, had been coy about taking part in the Tour.
The American cyclist has previously announced that he will race in the Giro d'Italia for the first time in 2009.
Armstrong overcame testicular cancer before his seven Tour victories.
In October the Tour de France organisers, the Amaury Sport Organisation (ASO), said Armstrong's return would be "embarrassing".
The American has also questioned how safe he would be in riding the Tour, expressing concerns about being targeted by fans.
Armstrong will end a three-and-a-half-year absence from the sport when he rides in the Tour Down Under in Australia in January.