Britain's David Millar said that a recent crash and over-training had left his confidence at an all-time low ahead of his bid for victory in the opening prologue of the Tour de France here Saturday.
The Saunier Duval rider, who is hoping to pull on the second yellow jersey of his career at the end of a "not too technical" 7.9km race against the clock, also expressed his support fora teammate who is suspected of doping.
Italian climber Leonardo Piepoli was on Thursday suspended by the Spanish outfit following a positive test for salbutamol during the Giro d'Italia.
The International Cycling Union (UCI) said Piepoli's test had produced higher-than-permitted levels of the drug, which is normally used to treat asthma but which at certain doses can have an anabolic effect.
Piepoli claims he took his asthma puffer to relieve allergies, and Millar - who returned to the peloton in June 2006 following a two-year ban for doping - was quick to lend his support.
"He's a rider I have a huge amount of respect for, and whom I trust," said Millar, who also feels sympathy for fellow salbutamol victim, Alessandro Petacchi, who also tested positive at the Giro for the drug.
"They are both being unjustly punished. Leonardo is a true professional who doesn't dope, he's an example for the younger riders and I find it ironic that a rider like him is in a situation like that."
Millar admitted to using the banned blood booster EPO (erythropoietin) several times in his career, but since serving a two-year ban the big Scot has returned to the peloton proclaiming he is 100 percent clean.
However his redemption appears to have had little effect on some other riders.
Cycling is in turmoil due mainly to dozens of riders being linked to the 'Operation Puerto' doping affair in Spain, which has recently led to a two-year ban for 2006 Tour of Italy winner Ivan Basso, and for the UCI to demand DNA samples from all riders racing the Tour.
A number of confessions, notably from 1996 winner Bjarne Riis, of doping practices have also shaken the sport - despite the widespread belief that the peloton was riddled with EPO in the 1990s when there was as yet no reliable test for the drug.
Millar admitted that since his comeback at last year's Tour, he has taken stock of his responsibility. And he will race this year fully aware that it is a crucial time for the sport.
"I don't think any of us can escape the fact that doping goes on in cycling. I have a reponsibility, I do talk about it a lot to journalists but I think we also have to look towards the future," he said.
"Although, we can't do that without also looking to what has gone on in the past."
He added: "It's slowly happening, with people admitting to errors they have made in the past.
"It's important for all the younger riders coming through, the likes of Mark Cavendish, not to have to experience somehing like this."
Ahead of Saturday's test, Millar said that a crash in recent months, followed by a spell of over-training, has left him feeling below par on the confidence scale.
"I'm riddled with self-doubt, which is new for me," added Millar, who is being tipped to win the prologue alongside fellow Brit Bradley Wiggins, and Swiss specialist Fabian Cancellara.
"But I do think the Brits have the home advantage. We've both been able to go over the course a few times - which I think is only fair!"
"It's not too technical, and there will be hardly any braking. It will be a question of going flat out for the whole eight (7.9) kilometres."
© AFP 20007