When nearly 200 athletes gather Saturday at the starting line of one of the longest and toughest races in the world, a single question will be on everyone's mind: Will he do it again?

Will he cross the finish line in first place after more than 2,000 miles and enter the record books in a blaze of color and guts and glory?

He is cyclist Lance Armstrong, the Texan who has won the famous Tour de France five times in a row. Only four other men have won the race as many times. Only one other has won it five straight times. And no one has won six.

To understand how incredible it would be for Armstrong to claim victory again, you need to realize that the Tour is beyond any bike race you could enter. What's the farthest and fastest you've ever gone on a 10-speed? Now think about riding almost 100 miles every day for three weeks at speeds that could risk a ticket -- even on the Capital Beltway.

The cyclists who make it to the end, sprinting their bikes down Paris's most well-known boulevard, will have ridden 2,087 miles. That's more than three-fourths of the way across this country, from Washington to Las Vegas, Nevada.

The Tour de France is really 21 races that circle most of France over 23 days. But how far riders travel isn't even the hardest part. Add in mountains. The Tour ascends into two of Europe's highest ranges, the Pyrenees and the Alps. There racers climb thousands of feet, sometimes several times in a single day. On the road down, they take death-defying descents at more than 65 miles per hour.

Cycling Hall of Famer Bob Roll calls the century-old Tour "the ultimate test to the human athletic animal, better than any car race, any running race, any ski race."

Bike racing might seem like the ultimate solo sport, but it's not. Twenty teams from Europe and one from the United States will compete this year, and the job of everyone except the team leader is to support that leader. Many great riders are nothing more than go-fers. They're responsible for bringing their leader food, breaking the wind for him so he can save his energy and protecting him from other riders. Guess who's the leader of the American team?

By July 25, the person in first place will have the fastest time over the entire course of mountains and straightaways. He will be the one in the yellow jersey.

If you see Armstrong wearing that color, he will have accomplished a stunning feat in sports history. But as amazing as winning would be, it's even more amazing to some that the 32-year-old is alive to race.

Less than a decade ago, he learned he had cancer that already had spread to his lungs and brain. Doctors gave him a less than 40 percent chance of surviving.

But Armstrong did survive, and he writes that his illness changed him and made him a better champion. Now he's not just a cyclist, but also a spokesman for people fighting cancer.

If anyone can break the Tour record, says Roll, "it's Lance Armstrong." Starting Saturday, millions of fans will be watching to see if he can do just that.

-- Susan Levine

Lance Armstrong celebrates his eighth birthday with his uncle, Alan.