Six-time Tour de France winner Lance Armstrong will retire after this year's race.
The Texan, who became the first man to win six Tours last summer, made the announcement ahead of competing in the Tour of Georgia, which starts today.
Armstrong is easily the most famous cyclist in the world after beating testicular cancer before winning his first Tour in 1999.
The 33-year-old said: "I have thought a lot about it, I have gone back and forth. My time has come but I will definitely have the itch every now and again.
"My children are my biggest supporters but at the same time they are the ones who told me it's time to come home. After July 24th, (continuing) is not an option. It's a great field, a great race, I would like to win again. I would love to go out on top."
Armstrong came back from being diagnosed with cancer in 1996 to win a record six Tour de France titles between 1999 and 2004. Three men - Jacques Anquetil (1961-64), Eddy Merckx (1969-72) and Miguel Indurain (1991-95) - won the event five times.
The announcement was widely predicted with the American struggling to maintain his spartan training regime in recent months.
He recently separated from his wife and has complained his career means he does not get to spend as much time as he would like with his three children.
Armstrong has also wearied after being drawn into a series of legal battles surrounding allegations that, although he has never failed tested positive in 13 years as a professional cyclist, he has taken performance-enhancing drugs.