Seven-times Tour de France champion Lance Armstrong will swap his bicycle for running shoes in tonight's New York Marathon, his first attempt at the 42.16km.
"Always in the back of my mind I had thought about doing a marathon," Armstrong said. "I did my first run two orthree days after I retired following the 2005 Tour. I understood I would lose my condition and put on 10 or 15 pounds but I didn't want it to get to 50.
"This was a logical step."
He is also raising money for his foundation and for cancer research. The 35-year-old American, who overcame cancer to win his seven Tour titles, said this was not the start of a new career.
One hundred runners signed up for Armstrong's team, raising more than US$600,000 (NZ$902,119.98). Former winner Alberto Salazar will pace him for the first 16km and ex-Olympic champion Joan Benoit Samuelson for the next 16.
Olympic 1500m and 5000m winner Hicham El Guerrouj will run with him for 10km before leaving Armstrong to finish in Central Park.
"It's not about being competitive, it's a personal goal. If I could break three hours I could leave happy."
Nine-times winner Grete Waitz, who has cancer, will present Armstrong with his medal, the same one given to all finishers in the 37,000-strong field.
