Olympic time trial champion Tyler Hamilton faces a ban for doping after failing blood tests in Athens and last week's Tour of Spain.
Hamilton is one of Lance Armstrong's main rivals
The 33-year-old American was found guilty of blood doping after winning the Vuelta's eighth stage, a time-trial, on 11 September.
Hamilton pulled out of the Tour on 16 September, citing stomach problems.
Hamilton told a news conference on Tuesday that he was "100% innocent" and planned to fight the charges.
"I'm devastated," he added. "My family, team, friends
are all devastated.
"I've been accused of taking blood from another person.
Anyone who knows me knows that is completely impossible.
"I can tell you what I did and did not put into my body.
Cycling is very important to me but not that important. If I
ever had to do that (doping) I'd hang the bike on the rack."
"I will fight this until I don't have a euro left in my pocket."
Andy Rihs, chairman of the board of Phonak, said he did not trust the new blood doping test.
"I don't believe in the test," Rihs said.
"I think this test was done sloppily and I am pretty clear that whatever the test comes out tomorrow (Wednesday) I stand behind Tyler."
A previous "A" test carried out in Athens on 19 August also reportedly showed up blood cell irregularities.
BLOOD DOPING EXPLAINED
What is it?
The administration of red blood cells to increase the blood's oxygen-carrying capacity
Injecting someone else's red blood cells; removing own blood and returning it once body has compensated by making more blood
Why would athletes do it?
The better the oxygen-carrying capacity of the blood, the better an athlete's endurance
Side effects can include:
Blood clots, overload of circulatory system, kidney damage, transmission of infectious diseases
Chances of being caught:
A new test can only detect the practice if the blood comes from a donor
A spokesman for Hamilton's Phonak team, said cycling's governing body the UCI had informed them Hamilton's tests showed "presence of a mixed red
blood cell population, indication of a homologous blood
In this case homologous means blood from another person.
The UCI is awaiting the results of a second "B" test on Tuesday designed to confirm the preliminary results.
And Hamilton's lawyer, Howard Jacobs, has criticised the decision to make the results of the "A" test public before the "B" sample was taken.
"The A-sample results should have never been made
public before the B-samples were done," Jacobs told USA Today.
"If the B-samples are negative, then there is no positive test, and they've
been dragged through all this for no reason."
Hamilton injured his back in a crash which led to his retirement during the 13th stage of the Tour de France in July, but bounced back to take Olympic gold in Athens.
He also famously went on to finish fourth in the 2003 Tour de France after breaking his collarbone in the first stage.
Blood doping is a method of increasing the number of red blood cells in the body which in turn carry more oxygen to the muscles.
In the past, blood would be removed from an athlete's system and then frozen and stored for several weeks before being reinjected into their system a day or two before a big race.
More recently athletes in endurance sports have used intravenously injected drugs such as erythropoietin (EPO) to get similar effects.