LUXEMBOURG -- Many speculate when Lance Armstrong gets tired of whooping Euro-butt every July he'll become a politician.

	After donning the yellow jersey on Sunday, Lance Armstrong let it -- and the pressure that goes with it -- slip away.

The three-time defending champion sure sounded like one at the start of the 2002 Tour de France, downplaying his chances of yet another victory despite being the top favorite to score a four-peat in the Super Bowl of cycling.

"I'm not guaranteed to be at the front. There could be somebody better than me. There could be 10 people better and I know that," Armstrong said before Saturday's start of the 89th Tour de France. "That's why I work hard, and that's why I train hard and prepare hard and that's why I still get nervous before the Tour de France."

"The day I show up and say, 'You're right. I'll be in front. I'm not nervous. I'm relaxed.' -- That's the day that you lose," said Armstrong, who came back from cancer to win three straight Tours. "There are 10 guys who can win this race."

His words, however, were betrayed by his performance in the opening weekend of cycling's toughest race.

Armstrong started where he left off at the end of last year's Tour -- in the yellow jersey.

	“	We hope to beat Armstrong, but until he has a bad day -- and he hasn't yet -- we cannot expect to beat him. ”
		— Joseba Beloki of Spain

The 30-year-old Texan blew over the short but dangerous 7-kilometer prologue course Saturday in the Duchy of Luxembourg, winning his 12th career Tour stage and his 36th day in the yellow jersey of the Tour leader.

"Armstrong was so strong today. It's obvious he's the best," said David Millar, a British rider who beat Armstrong in the 2000 prologue. "The only thing that's going to beat him is an accident or a really bad day."

After the second stage he was still near the top, in fourth place. Armstrong enters the 89th Tour as the heavy favorite. With the absence of such stars as Marco Pantani and Jan Ullrich, Armstrong is the only racer out of the 189 riders on 21 teams who's won the Tour.

A posse of Spanish riders vows to topple Armstrong and there's some talk of an all-American podium, with Tyler Hamilton and Levi Leipheimer perhaps joining Armstrong on the final podium in Paris.

Armstrong is at the peak of his powers and seems unbeatable. No one carries the wallop of Armstrong: strong in the mountains and deadly in the time trials. A winner of the Midi Libre and the Dauphine Libere races earlier this summer, many say the only race at the start of the 20-stage, 3,277-km race across France is for second place.

"Armstrong is the favorite. There is no one who can beat him, at least so far," said Spain's Joseba Beloki, third overall in 2000 and 2001. "We hope to beat Armstrong, but until he has a bad day -- and he hasn't yet -- we cannot expect to beat him."

	“	One has to respect this race. It has a tough route with a lot of mountains and I haven't won anything. Everything is ahead of us and I have to fight every day. ”
		— Lance Armstrong

That assumption of power worries Armstrong, who's savvy enough to know that winning the Tour is no easy feat. A flat tire, a bad day, an accident or a missed breakaway can spoil the Tour for anyone. He refuses to believe the pundits who say the race is over before it starts.

"Tour de bore?" Armstrong said. "Yeah, I've heard that. If everyone says the race is for second place. That makes me nervous and scares me. If you think you're the favorite, that's when you lose big. I'd prefer to stay hungry.

"I worry that people will say that I have won my fourth Tour, because it hasn't happened yet. One has to respect this race. It has a tough route with a lot of mountains and I haven't won anything. Everything is ahead of us and I have to fight every day."

In Sunday's first stage, Armstrong let the yellow jersey -- and the pressure that goes with it -- slip away. His only worry during the first week of flat stages is to stay out of trouble. The Tour is won and lost in the mountains. All six difficult mountain stages are packed in between July 18-25, late considering only three days remain in the race by the time the peloton leaves the Alps. Last year, there was nearly a week left in the race after the final mountain stage.

The Tour gets steep in the Pyrenees for two summit finishes July 18-19 and visits an old friend at Mont Ventoux, a long, punishing stage that ends on a lunar landscape high above France's Provence region on July 21. Three more hard climbing stages in the Alps wrap up the mountain stages July 25. After a final time trial, the Tour concludes on the cobbles of the Champs Elysees on July 28.

Armstrong's not sweating it. He's on top of the world. He's found the winning recipe for the Tour de France. He's found wealth and fame. He earns an estimated $15 million a year. He flies with the president on Air Force One. He rides motor-cross bikes with singer Lyle Lovett in Baja Mexico and has movie-star friend Robin Williams join him every year at the Tour.

More than anything these days, however, Armstrong is a family man. For a man who grew up without a father, Armstrong is intent on being the father he never had.

Armstrong was surrounded by family and friends during the weekend. His wife, Kristin, and their three children watched as a fit-looking Armstrong rode the rollers. His son, Luke, fetched water bottles for cycling's man of the moment.

"It becomes harder and harder for me to leave and go to the races and leave the children, so when they can come it's special," Armstrong said. "My motivation is to do my job and do it for them."

No one's been able to stop Armstrong yet. The cycling world has until July 28 to try one more time.

Andrew Hood is a freelance writer from Colorado who spends a lot of time chasing cyclists across Europe. This is his fifth Tour de France for ESPN.com.