TOULOUSE, France -- Lance Armstrong is chasing history in this year's Tour de France, but midway through the three-week, 2,000-mile romp, Armstrong finds that he's the one being chased.

	Lance Armstrong holds a 21-second lead -- not the comfortable margin he's used to.

The 31-year-old Texan survived three hard stages in the French Alps with the race leader's yellow jersey. In his quest to win the Tour a record-tying fifth time, Armstrong has a fight on his hands and, for the first time since his dramatic cancer comeback in 1999, he looks beatable.

"We see now Armstrong is human after all," said Enzue Usebio, director of the Spanish Banesto team. "Armstrong doesn't look as strong as he has in the past. I think he will be weaker in the Pyrénées later in the race."

Armstrong enters Friday's crucial individual time trial with a narrow, 21-second lead over second-place Alexandre Vinokourov (Telekom). For Armstrong, who is used to racing the final half of the Tour on cruise control, that's downright close.

"It's normal that people say Lance is beatable," said Dirk Demol, assistant director at Armstrong's U.S. Postal Service team. "Everything is open in the Tour. It's never happened like this before that after the Alps everybody is so close together."

There's no doubt this year's Tour is the most thrilling in years.

There's been spills, stirring attacks, spine-tingling racing and Armstrong's "great escape" when he went 4-wheeling to avoid a crash in Monday's Stage 9.

With four brutal days looming in the Pyrénées, this Tour's far from over.

New faces challenging Armstrong
Of course, looking beatable and actually beating Armstrong are two very different things.

Armstrong has the experience, the team and the desire to win cycling's greatest race. That formula pushed him to four consecutive Tour victories.

"I am perhaps not as strong as the other years," Armstrong admitted after the epic stage to Alpe d'Huez on Sunday, when he let Iban Mayo slip away for the victory. "I do feel a year older, a few more gray hairs. Maybe I get out of bed a little slower than 3, 4, 5 years ago, but I still feel strong."

This Tour is already littered with would-be usurpers to Armstrong's Tour throne who -- either by crashing, illness or poor form -- are out of the race or at least marginalized to the point where they're no longer threats.

Tour of Spain champion Aitor Gonzalez, Giro d'Italia champion Gilberto Simoni, Colombian climber Santiago Botero, American Levy Leipheimer and Spanish rider Joseba Beloki are among the major names that Armstrong won't have to worry about anymore.

"They underestimated the Tour de France," Armstrong said referring to Gonzalez and Simoni. "They've got to understand that the Tour de France is not the Giro and it's not the Vuelta. To say that without experience takes some nerve. I mean, these guys can certainly figure on the Tour, but not this year."

Beloki's horrendous crash on the final hill rolling out of the Alps on Monday was one of the worst accidents for a Tour contender in years. Last year's runner-up roared into a twisting descent too fast, hit the brakes on slippery, sun-baked tar, lost control of his bicycle, causing his rear tire to explode, and then "high-sided," or flipped forward over his bike and smashed so hard on the pavement he broke his right elbow, wrist and femur.

Armstrong was just 20 feet behind Beloki, but a dazzling display of bike-handling skills in his impromptu off-road detour that sent the yellow jersey bouncing across a French hay field saved his skin.

He could have crashed into Beloki, or struck a fence, a tree, a culvert, rocks, a ditch or a policeman -- all things Armstrong deftly avoided in what's already being called cycling's great escape. Armstrong then vaulted over a steep ditch and rejoined the race with barely messing up his uniform.

Nipping at Armstrong's heels this year are a bunch of Tour no-names, riders who've had success in other races, but never on cycling's biggest stage.

"The Tour always has surprises," said Armstrong, who finished safely in the main bunch Thursday to retain the yellow jersey. "People come up and people go down and you see it every year, either through a miscalculation of their form or bad luck. But at the end of the day, you still have to win the race."

There were eight riders within three minutes of Armstrong at the Tour's halfway point, a time gap considered within easy striking distance for the world's fittest racers.

Second-place rider Vinokourov looks to be a serious podium contender. A winner of Paris-Nice, Amstel Gold and the Tour of Switzerland, the Kazakh racer is inspired, riding in the name of compatriot Andrei Kivilev, who died while racing in March.

Spanish rider Iban Mayo is an even larger unknown figure. Mayo didn't finish the only other Tour he's started, but he dogged Armstrong throughout his win June's Dauphiné Libéré race in France.

Mayo dropped Armstrong in Sunday's epic stage to Alpe d'Huez in front of an estimated 450,000 fans lining cycling's most famous climb. Mayo made up more than two minutes on Armstrong, the first time a Tour contender has gained on Armstrong in a major climb.

"People think that he's not as strong as he has been because he wasn't able to make big time differences in the Alps like he has in the past," said Spanish rider Iban Mayo, a dangerous rival sitting in third at 1 minute, 2 seconds. "After the time trial, if he's not strong like other years, everyone will be attacking hard in the Pyrénées."

Former teammate Tyler Hamilton is riding with incredible courage and tenacity, sitting fifth overall at 1:52 back while racing with a fractured collarbone from a spill in the Tour's first stage.

Former Tour winner Jan Ullrich is also hovering in the background, sitting comfortable in sixth place after enduring two days of fever in the Alps.

The Pyrénées loom behind time trial test
The Tour enters what's sure to be the decisive week of the centenary edition. Friday's time trial is followed by four punishing stages in the Pyrénées over five days.

"The Tour will be won or lost in the Pyrénées," says Hamilton, who previewed the stages in May and June. "Two mountain-top finishes, narrow roads, hard stages, it's going to be very difficult."

Friday's 47-kilometer time trial is important litmus test for Armstrong.

He needs to gain valuable time against the lithe climbers before heading into the Pyrénées. Armstrong's only lost one long time trial in his four-year Tour dominance -- and that was only by 11 seconds last year to world time trial champion Santiago Botero.

If he doesn't have his trademark dominance, his rivals will spell blood and pounce in the Pyrénées.

"I think it's going to be the most important time trial I've ever done in the Tour," Armstrong said. "I've seen the course, know it pretty well and I'll see it again on the morning of the race."

This year's Tour has a new twist after race organizers played with tradition. En route to four Tour victories, Armstrong typically would have a nice pad against the climbers because one of the time trials was held before the first mountain stages.

Not this year. Tour organizers bumped the first time trial after the Alps, a move which lived up to its promise to keep some suspense in the race.

"Two time trials after the mountains is very different, but to have (60 miles) of time trials after the Alps is a good thing," said Johan Bruyneel, U.S. Postal's director. "The Tour de France is a three-week race. We still have half the race left. You can't say too much after just a few stages. The goal is not to be the best in a stage, but to win the Tour."

Hamilton and Ullrich will likely finish with about one minute to Armstrong in the time trial, but climbers such as Mayo and Francisco Mancebo (fourth at 1:37 back) could lose more than two minutes.

Saturday's 197.5-km climbing finish to Ax-3 Domaines is an explosive stage featuring what some are calling the hardest climb in this year's Tour up the Port de Pailhéres with 29 kilometers to go.

Sunday's 191.5-km rollercoaster hits the difficult Col de Peyresourde before a dangerous downhill plunge to the finish line in Loudenville. Monday's short but punishing 159.5-km climb hits the legendary Col de Tourmalet before finishing on the summit at Luz Ardiden.

Following the final rest day on Tuesday, the peloton hits two final climbs in the Pyrénées in the French Basque region before a flat finish into Bayonne.

From there it's four flat days back to Paris. If Armstrong doesn't have the Tour in the bag by then, there's the final individual time trial on the Tour's penultimate stage.

Like Armstrong always says, the Tour's never over until the final lap on the Champs Élysées. Getting there in yellow this year is going to be a little more complicated for Armstrong.

Andrew Hood is an American freelance journalist based in Spain and has covered every Tour since 1996.