Lance Armstrong has dismissed his chances of a fairytale victory in his comeback to professional cycling at the Tour Down Under in Australia.

The seven-time Tour de France winner said he had no real hope of winning the Jan. 20-25 race in South Australia and his only real ambition was to be competitive.

"I think it would be unrealistic to expect a victory," the American told a news conference in Adelaide on Monday.

"I hope to be in the mix, I could be completely wrong, I might be the first guy dropped."

Armstrong quit professional cycling after the 2005 Tour de France but announced late last year he was making a comeback at age 37 to help promote cancer awareness.

A survivor of testicular cancer, Armstrong chose the Tour Down Under to launch his comeback and his participation has generated unprecedented interest in a race he said used to be "obscure".

"With the pro-Tour status and now with a climate like this, a terrain like this and a competitive field, I realise that it makes no sense not to start the season here," he added.

He arrived in Australia under the sort of tight security normally reserved for heads of state before fronting a packed news conference.

Armstrong said there had been times when he questioned the sanity of his decision to make a comeback but was motivated by his campaign to help cancer sufferers.

"For me it's not so much a sporting challenge, and it's not a financial challenge, it's not any of those things," he said.

"I came back as a volunteer and so I'm here for the love of the bike and the passion of the cause."

Armstrong said he had still retained his competitive instinct and had trained harder than ever to get himself in shape for the six-stage event.

PEAK FITNESS

"The tests that we do on the bike, or on the road, or in the lab indicate that my January fitness is much better than it ever was the years when I was winning the Tour," he said.

"But that doesn't mean anything until you get into the race."

Armstrong finished his training in Hawaii to fine-tune himself for racing in South Australia, where temperatures are forecast to climb above 40 degrees Celcius.

Shortly after his arrival, the Texan went for a four-hour ride in the hills surrounding Adelaide but said his fitness levels were the least of his concerns.

"I have a little bit of insecurity and a little bit of nervousness there," he said.

"I'm fairly fit, but it's not just about your physical condition. It's about 200 guys going down the road and going around dangerous corners at 40-50 miles an hour -- and how does that feel?

"Those are the things that most people look at and think we're nuts to do this."

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