Seven-times Tour de France winner Lance Armstrong has dismissed claims by former team-mate Floyd Landis that he used performance-enhancing drugs.
Landis, who was stripped of his 2006 Tour victory after a positive test for testosterone, has confessed to using performance-enhancing drugs and accused others, including Armstrong, of doping.
"We have nothing to hide. We have nothing to run from," Armstrong, who was Landis's team leader at U.S. Postal, told reporters before crashing out of Thursday's fifth stage of the Tour of California.
"(The allegations) they're not even worth getting in to. I'm not going to waste your time or my time. I think history speaks for itself here. We've all followed this case (Landis) for the last four years."
Armstrong, who was taken to hospital after a heavy fall early in Thursday's stage, said Landis, had no credibility.
"This is a man that's been under oath several times and had a very different version," Armstrong said.
"This is man that wrote a book for profit that had a completely different version. This is somebody that that took, someone said close to a million dollars, from innocent people for his defence under a different premise.
"And now when it's all run out, the story changes. So we're a little confused."
Armstrong has had to fend off accusations of doping before but has never failed a drugs test and always denied taking banned substances.
"It's our word against his word," Armstrong said. "I like our word. We like our credibility. Floyd lost his credibility a long time ago."
A survivor of testicular cancer, Armstrong won the Tour de France a record seven times between 1999 and 2005 before retiring.
He made a comeback last year at the age of 37, finishing third in the Tour, and is aiming for an eighth win this year after forming his own team, RadioShack.
