David Millar admits his over-riding feeling will be one of shame when he lines up at the start of the Tour de France after a two-year doping ban.
David Millar prepares for Saturday's prologue
The Scot makes his return to competition in Saturday's 7.1km prologue in Strasbourg.
"I'm a little bit apprehensive," the 29-year-old conceded on Thursday.
"I had a lot of respect from the professional peloton before, but now I have to earn it. If anything, I'm ashamed more than anything else."
Millar was banned following his admission that he took the banned substance EPO to help him win the world time trial in 2003.
But he claims to be a reformed character and wants others to learn from his mistakes.
"I hope the message gets sent out that it is possible to win the biggest races in cycling without doping," he added.
"I think the most important thing is to show that to young professionals coming into the sport.
"I want people to know I am doing this 100% clean. It could take years for people to believe me. But I want what happened to me to be a positive story."