Yellow jersey favourite Alberto Contador could strike a first psychological blow to his Tour de France rivals when he lines up for the first stage, a 15.5km time trial, on Saturday,

However the Spaniard is up against the might and determination of Swiss Olympic champion Fabian Cancellara, who has vowed to do everything he can to stop Contador from claiming the Tour's first big prize.

Cancellara normally excels in longer time trials but, as shown over the past few years, there seems no end to the Saxo Bank rider's palette of talents.

Formerly a one-day race and time trial specialist, recently, he won the Tour of Switzerland - a race normally reserved for the more all-round riders who excel on the climbs.

Cancellara admitted he has not ridden over the technically-demanding Monaco time trial course, but the Swiss says if he is on form he will be difficult to beat.

"I feel in good shape and that's all that really counts now. I know how strong I am and when I feel this strong, I don't need to go out and know the whole race course," he said Wednesday.

If Cancellara wins he is likely to try and defend the yellow jersey at least until the next big rendezvous, the team time trial over 39km held on the fourth stage.

But if Contador triumphs, it could give the Spaniard a cushion of comfort ahead of three testing days of climbing in the Pyrenees, beginning on stage seven.

And it will help put paid to recent speculation that his team-mate Lance Armstrong, the record seven-time champion, may at some point take over the team's leadership.

In the Pyrenees Contador and his Astana team are likely to play a major role in the first skirmishes in the mountains as the fight for command heats up.

Also in contention on Saturday will be Australia's two-time Tour de France runner-up Cadel Evans, who produced some scintillating riding at the Dauphine Libere race.

But with all the yellow jersey favourites keen to limit their losses on the first stage, most of them - including defending Tour champion Carlos Sastre and Russian Denis Menchov - will hope to finish among the top ten.