When Lance Armstrong sets off Saturday in his quest for a record-breaking sixth victory in the Tour de France, he will be dogged by more than a pack of younger riders snapping at his heels.
He will also be pedaling under a cloud of fresh doping allegations against him, amid a wider scandal that has barred some top teams and riders from competing in this year's Tour. Some experts say those charges may drive, rather than distract, Armstrong's ambition.
"He is furious" about accusations in a new book that he has used performance-enhancing drugs, says Jeremy Whittle, editor of the British monthly magazine Procycling. "If he can produce the kind of strength of character and competitive rage" that propelled him last year, "he can do it."
The charges of Mr. Armstrong's drug use - echoing similar allegations about other top US athletes in recent weeks - come in "L.A. Confidential: The Secrets of Lance Armstrong," a book written by a top British sportswriter and a French colleague.
The authors quote Armstrong's former masseuse, who insinuates that in 1999 he took EPO, a banned drug that boosts oxygen-carrying red blood corpuscles, and tells how she collected unidentified tablets for him in Spain and disposed of his syringes.
A former colleague of Armstrong's in the Motorola team in 1995, the New Zealander Steven Swart, also accuses the US rider of approving a team decision to use EPO. "He's sold his fairy tale to everyone that he's as pure as snow, but there are a lot of gaps that he hasn't filled in," Mr. Swart told the New Zealand Herald.
Armstrong, threatening to sue the book's authors and their sources, has decried their allegations as "absolutely untrue. I can absolutely confirm that we don't use doping products," he said two weeks ago at a press conference. His supporters point out that a two-year French police investigation of Armstrong's alleged drug use was closed without any charges being leveled.
But the US rider, whose recovery from cancer and five consecutive Tour victories have made him a hero to millions, is finding it increasingly hard to make his claims of innocence heard over the din of recent doping scandals that suggest illegal drug use is widespread in professional cycling.
Time trial World Champion David Millar was banned on Monday from this year's Tour because he was taken in for questioning by French police following up their discovery of banned drugs at the offices of Cofidis, Mr. Millar's team.
Millar is one of eight Cofidis members under investigation, implicated by the testimony of fellow rider Philippe Gaumont, who has told investigators and the press that doping with steroids, human growth hormones, EPO, and amphetamines is systematic on his team.
His allegations match those of another cyclist to have broken his profession's code of silence, Jesus Manzano, a Spanish rider who told a Madrid sports paper last March that he had been forced by his team, Kelme, to take banned substances during last year's Centennial Tour. He also went into considerable technical detail about how riders avoid detection.
Tour organizers subsequently banned Kelme from this year's race, in a bid to stave off a repetition of 1998's "Tour of Shame," when police found a Festina team car's trunk full of illegal substances. That race was marred by police raids on riders' hotels, a sit-down-strike by the cyclists, and the withdrawal of several teams.
Some in the cycling world seem resigned to the situation and say it is not very different from that in other sports. Doping "has always been a part of cycling and I guess it always will be," says Steve Bauer, a Canadian rider who wore the Tour de France leader's yellow jersey 14 times during his career.
"There really isn't anything that can be done to curtail doping 100 percent," he adds. "So it won't be a fair playing field and if you want to be at the top there is an incentive to look at that route."
Trying to cut off that route, the International Cycling Union has warned it may carry out new blood tests during this year's Tour to check for banned blood boosters and hormones, hitherto undetectable.
Others fear that repeated doping scandals are sapping public support for cycling and say only drastic changes to the sport's culture can root out illegal drug use.
"The biggest problem is that people in team management are ex-riders who have a culture of behaving in a certain way," says Procycling's Mr. Whittle. "It will take draconian measures to get rid of the people who are incapable of change." Now, he says, "It is like an arms race. [Cyclists] are all looking at each other saying 'I wonder what he's on?' "
Little is likely to change, however, either in cycling or in the Olympic Games, while sports authorities themselves are in charge of drug testing, argues Jean-Pierre de Mondenard, a sports doctor who was in charge of drug controls at the Tour de France in the 1970s and says such tests are a joke.
"Saying you have never been caught out by a dope test is not the same as saying you are clean," he says. "There are so many products that can't be traced, or that can be masked."
"Cycling needs someone from outside the business to come in and kick over the anthill to find out what is going on," he insists. "How can you expect people whose priority is to maximize a sporting spectacle to commit harakiri by catching out cyclists? It is impossible to be a spectacle promoter and a guardian of sporting ethics at the same time."
That dilemma, Mr. Mondenard suggests, explains why Cofidis is still expected to participate in the upcoming Tour, despite its savaged reputation: It is a popular French team containing a number of well-known riders.
For almost everyone watching the three-week-long, 2,120-mile race, however, one question will be paramount: Can Lance Armstrong do what no man has ever done before - win the toughest two-wheeled challenge in the world six times?
Four others have won five times, and one of them, the Spaniard Miguel Indurain, has won it five times in a row, like Armstrong. But none managed to win after the age of 31, and the American is now 32, older than most top-level cyclists.
Still, Armstrong's performances have always relied as much upon preparation, grit, and single-mindedness as on his physical form.
Armstrong's perennial nemesis Jan Ullrich - who has been runner-up five times - will be waiting to exploit any sign of weakness in the American. "If riders see a window of opportunity they will be more confident to take the chance" this year, says Mr. Bauer. "His biggest weakness is that other riders know he can be beat."
But, he says, "The Tour is his only objective, maybe the last huge one of his career."