Armstrong will take part in the second race of his comeback in California
Lance Armstrong has split with leading American anti-doping expert Professor Don Catlin ahead of the Tour of California, which starts on Saturday.
The seven-time Tour de France winner was set to have a personal anti-drugs programme administered by Catlin.
But the American rider said the cost and schedule involved in working with Catlin made the plan impossible.
However, Armstrong insists he will still have the most comprehensive anti-doping programme in the world.
He will instead work with Danish scientist Ramsus Damsgaard, who conducts testing for Armstrong's Astana team.
Armstrong said: "It was a difficult programme to put together.
"It was complex. If you match his [Catlin's] schedule with mine, with travelling all over the world, the testers literally would have been tripping over each other to get to the room.
"That's not to say we won't have the most comprehensive anti-doping programme in the world."
Armstrong still plans to continue publishing the results of his personal anti-doping programme on the internet.
He put the the results of seven recent blood tests on his website www.livestrong.com on Wednesday.
Armstrong has been the subject of doping allegations during his career but has always strongly denied any wrongdoing.
The 37-year-old will continue his comeback to cycling in California after three years away from the sport.
In his first race back last month Armstrong finished 29th to overall winner Allan Davis of Quick Step in the Tour Down Under in Australia.
Armstrong says he is in good shape for the nine-day 1,250km race in his homeland.
"Now I'm fresh. I feel as good now at age 37 as I did at age 27," he said.
"It's not the body, it's the mind that drops off and says 'I've been doing this for 20 years, I don't want to do this any more.'"
The event starts with a time trial in Sacramento on Saturday and ends on 22 February in Escondido, south of Los Angeles.
The field includes Armstrong's compatriot and defending champion Levi Leipheimer, last year's Tour de France winner Carlos Sastre of Spain, and 2006 Giro d'Italia victor Ivan Basso, who returned in October after serving a two-year doping ban.