Alberto Contador has the potential to be as big as Lance Armstrong, but a failed dope test has left his future in cycling hanging in the balance.
The Spanish three-times Tour de France champion, still only 27, faces an uphill battle to clear his name.
A man of few words, Contador must raise his voice for once to be heard in a sport whose image has already been much damaged by doping scandals.
Before announcing he had tested positive during this year's Tour for the banned anabolic agent clenbuterol, Contador had never let anything distract him from his goals.
"He is always motivated. He never races just to race. Always going for the victory, always fighting. And lots of riders do many races just for training. Quite a disciplined rider, his routine is never disturbed," Astana soigneur Yuriy Kulishkin said.
Contador, who survived a serious illness six years ago and whose younger brother suffers from cerebral palsy, has a boy-next-door image.
"One day, when we were having diner with sponsors and a lot of people, Alberto had to leave the table because he did not want to get to bed too late," his Astana team manager Yvon Sanquer recalled after this year's Tour de France.
"He got up and took the time to shake everyone's hands and had a word for every one of them."
But the dark-skinned, serious-looking Contador is as sparkling on the bike as he is discreet in everyday life.
In the 2009 Paris-Nice, one day after all but losing the race, he jumped out from the gun in a desperate attempt to beat his rivals -- an extremely rare move in modern cycling.
Contador has mixed with controversial figures in the sport, starting his career under the guidance of fellow Spaniard Manolo Saiz, who was arrested in 2006 in the Operation Puerto blood- doping scandal. Contado considers Saiz as a second father.
He joined Discovery Channel in 2007, claiming his maiden Tour title under Johan Bruyneel, the man behind Armstrong's record seven triumphs.
That year, he was grilled about his possible involvement in the Puerto scandal after reports said his name appeared in files of the investigation.
Contador strongly denied any involvement and was never formally charged. The following year, he could not defend his title after Astana was banned from the race because of its past doping record. But he won the Giro and the Vuelta to become only the fifth rider to win in all three grand Tours.
Contador went on to win the Tour in 2009 and again this year but on July 21 he failed a dope test for clenbuterol and although the concentration was minimal, he could face a two-year ban.
The quiet man is ready for a fight to clear his name.
"Right now I'm not worried about my Tour results, I just want this all to be cleared up so my family can stop worrying so much," he said.