Tour de France podium finisher Frank Schleck has confirmed that a second 'B' sample has tested positive for a banned diuretic but denies any wrongdoing.
Luxembourger Schleck, who finished third overall in last year's race, quit the Tour in disgrace on Tuesday after being informed by the International Cycling Union (UCI) of a positive test for Xipamide.
Although under UCI rules the 32-year-old could have continued in the race, his embattled RadioShack team sent him home.
Diuretics are not considered performance-enhancing but can be used to help riders lose weight, and therefore perform better in the tough mountain stages of the race.
More ominously, they can also conceal the presence of a banned drug by helping to flush it from the body through increased urination. Xipamide, a diuretic, is normally used for the treatment of oedema and hypertension.