Armstrong defiant on doping claims

ADELAIDE, Australia - Lance Armstrong said on Saturday he was losing no sleep despite the threat of a federal investigation into alleged doping practices casting a cloud over his stunning career.

"It has no effect on my life - zero," said the American, who will wind down his 20-year cycling career with the Tour Down Under this week.

So far, Armstrong has been "humbled" by the public support he has received in Adelaide, he said, as well as "amazed" by Australia's reaction as the northeast of the country reels from the impact of deadly floods.