The American cyclist Floyd Landis finds out today whether his backup "B" sample tested positive for doping - a result which could cost him the Tour de France title and lead to a two-year ban.
The International Cycling Union is expected to announce the results at after testing is completed at the Chatenay-Malabry laboratory, which is accredited by the International Olympic Committee and World Anti-Doping Agency.
Landis and his defence team expect the sample will confirm a July 20 urine test showing he had an elevated testosterone ratio after making a remarkable comeback and winning the 17th stage of the Tour in a solo breakaway in the Alps.
"We think that it can confirm the 'A' sample," lawyer Jose Maria Buxeda said when testing began.
But Buxeda still believes Landis will prove his innocence even if the backup sample is positive.
"He's pretty sure we will be able to prove, if this result is confirmed, that it is due to natural causes," Buxeda said.
If the test is negative, Landis would be cleared. If it's positive, the UCI will refer the case to the U.S. Anti-Doping Agency for handling. The process could take weeks or months, including possible appeals to the Court of Arbitration for Sport.
If Landis becomes the first Tour champion stripped of victory, the title would go to Spanish rider Oscar Pereiro.
Landis, a 30-year-old former mountain biker, says he was tested eight other times during the three-week tour and all the results came back negative.
"I'm going to do my best to defend my dignity and my innocence," he said on CNN's "Larry King Live" last week.
Landis has hired high-profile American lawyer Howard Jacobs, who has represented several athletes in doping cases.
Since July 27, the explanations of why Landis turned up an testosterone-epitestosterone ratio of 11:1 - well above the 4:1 limit - have varied.
Was it the beer and whiskey he consumed after crumbling and losing the yellow jersey on July 19, or his natural metabolism that caused the high reading? Could it be thyroid medication linked to his ailing hip?
Now, dehydration is the latest possible reason offered.
That was quickly rebuffed by several of the world's top anti-doping officials and contrasts with events during stage 17 - when Landis drank huge amounts of liquid and splashed his face with water.
"That reason doesn't make any sense. The ratio is already taking something like dehydration into account," said David Cowan, director of the Drug Control Center at London's King's College. "If you're dehydrated, you produce less urine, but it's not as if you're producing less epitestosterone or testosterone - the levels should remain the same."
Earlier this week, a New York Times report said that a second analysis of Landis' "A" sample by carbon isotope ratio testing had detected synthetic testosterone - meaning it was ingested.
Although "B" samples rarely contradict the original finding, there have been some exceptions.
In September 2005, the Phonak team reinstated Italian rider Fabrizio Guidi after his backup test came back negative for the endurance-boosting hormone EPO.Reuse content