Lance Armstrong starts Tour gamble in Monaco

MONACO (Reuters) - Lance Armstrong will begin to find out whether his gamble to return to the Tour de France is a credible one when the seven-times champion tackles a tough opener in front of Monaco's casino on Saturday.

Organizers broke with the tradition of short prologues by staging a 15.5-km first act which could allow the stage winner to keep the coveted race leader's yellow jersey for some time.

"In 2005, on such a course, I would have destroyed the race and made huge gaps," said Armstrong, who returned to racing in January after 3 1/2 years in retirement.

"It's a good course for me, hard and technical. I've lived here. I know the roads like the back of my hand. But it's no longer 2005," the American, who has attracted more attention in the last few days than the principality's royal family, told sports daily L'Equipe.

The first half of the course is uphill and includes a fourth-category climb in Beausoleil before a long descent back to the Monaco port.

Former prologue winner Bradley McGee forecast a fight between 2007 Tour champion Alberto Contador and Olympic time trial gold medalist Fabian Cancellara.

"The outcome will depend on how Contador handles the descent and how Cancellara handles the climb," he said.

(Editing by Julien Pretot and Alison Wildey)