Alexandre Vinokourov's backup sample has confirmed the original finding of a banned blood transfusion, the Associated Press reported.
The Kazakh rider and his Astana team were forced out of the Tour on Tuesday, when it was revealed Vinokourov had failed a doping test. Last Saturday, he tested positive after winning a time trial. Monday, Vinokourov also won Stage 15, a tough climb in the Pyrenees.
He faces a two-year ban from cycling and could lose a year's salary under the cycling governing body's anti-doping charter.
In Saturday's 19th stage, Spain's Alberto Contador all but locked up a victory by holding off his top rival in the final time trial, though he became the latest rider to feel the sting of the doping allegations that have marred the race.
American rider Levi Leipheimer, a Discovery Channel teammate of Contador, won the stage in 1 hour, 2 minutes, 44 seconds in the 35-mile race against the clock from Cognac to Angouleme.
Contador, 24, lost most of his lead but still holds a 23-second advantage over Cadel Evans. Barring a crash or other mishap, Contador is likely to bring home the yellow jersey today in the 20th and final stage, a 90.7-mile ride from Marcoussis to Paris' Champs-Elysees that is usually a processional ride with few chances for breakaways.
"I'm eager to go home and celebrate," said Contador, who was encouraged during the time trial by seven-time champion Lance Armstrong, who has ties to Discovery and was riding behind in a team car. "It wasn't an easy day."
The latest doping allegations didn't help.
French daily Le Monde, citing what it claimed was an investigation file it had access to, said Saturday that Contador's name, or initials, appeared in documents found at the apartment of Spanish doctor Eufemiano Fuentes, at the center of the Spanish doping probe known as Operation Puerto.
Contador said he was "sure" he was not involved in the case.
He said he would, if asked, give a DNA sample but added he wouldn't offer it up himself.
"I'm innocent," he said. "I don't have to prove anything to anyone."
Earlier Saturday, Vinokourov announced he would fight any blood doping charges.
"Never before this year's Tour de France have I ever been accused of violating any doping law," Vinokourov said in a statement released by his attorney, Maurice Suh. "I have been tested at least 100 times during my career. These test results simply make no sense. Given all the attention paid to doping offenses, you would have to be crazy to do what I have been accused of, and I am not crazy."
Blood transfusions work by increasing an athlete's count of red blood cells, which carry oxygen to the muscles.
Tracking the 94th Tour
Stage 19: Time trial took riders over 34.5 miles of flat roads from Cognac to Angouleme to the finish in Paris.
Winner: American Levi Leipheimer
Yellow jersey: Spain's Alberto Contador
Today's final stage: A 90.7-mile ride starting from France's rugby center in Marcoussis and ending on the Champs-Elysees in Paris.
TV: 7:30 a.m., Versus; 1 p.m. Ch. 10 (taped)