David Millar has admitted he is unsure of his form for the Tour de France, saying he feels he is about to dive into an abyss as he starts the race.

Speaking in a press conference in the Excel media centre on Friday, Millar said he has struggled to find good form during the season and is very doubtful about how well he can perform in Saturday?s prologue time trial.

?I?ve had a horrible time, I?ve never spent as long feeling terrible on a bike,? Millar said emotionally.

?It?s been hard to pin point just what the problem is and I?ve spent eight weeks doing tests. A lot of it was probably down to fatigue and I came back from injury in May and maybe over did it. I overloaded with races and it?s all accumulated. Since the Dauphine I?ve just tried to recover as much as I can.?

?It?s also psychological and I?m terrified about under performing and just want to try and forget the last two months. It?s affected my confidence a bit and I?m not as self confident as I usually am. In fact I?m riddled with self-doubt, which is rare for me. I?m hoping my experience can help me manage things but it feels like I?m going into an abyss and I can?t predict what?ll happen. That?s a bit discerning.?

Millar said he has worked with British Cycling?s Matt Parker to taper down for the Tour de France. He saw the route of the prologue time trial a couple of weeks ago at seven o?clock in the morning and confirmed that riders will hardly touch their brakes as they fly at 50km/h round the course. Millar listed five riders who he believes are the favourites to win the prologue.

?I think it?ll be between Bradley (Wiggins), Cancellara, Zabriskie, myself and maybe Stefan Schumacher. In a way me and Brad have got a slight home advantage because we?ve been able to ride the course.?

Asked about doping, Millar again made his position clear but called on the sport to accept the past as a way of facing the future. Surprisingly he also defended team mate Leonardo Piepoli who was suspended By Saunier Duval on Thursday after the UCI confirmed his positive for Salbutamol.

?My first objective is always the racing but none of us can escape the doping problems going on at the moment,? Millar said.

?I talk to journalists about doping a lot and try to bring a positive aspect to it and look to the future. I think we?ve learnt we can?t move to the future unless we accept the past. Some people are admitting their errors and not a day goes by when I don?t think about the big picture. My generation of riders shouldn?t forget that big picture so that other generation of riders such as such as Mark Cavendish never have to deal with all this. It?s not fair they have to deal with our baggage.?

?I want to publicly support Leo Piepoli. He? going through hell but I have a lot of respect or him and trust in him, like I do for Alessandro Petacchi. They?re great riders who are being unfairly punished.?