PERPIGNAN, France: In less than 48 hours, Lance Armstrong will have answered the last unresolved question about his capacity to win an eighth Tour de France: Can he still climb?

Astana rider Lance Armstrong of the US awaits the start of the fifth stage of the 96th Tour de France cycling race between Le Cap d'Agde and Perpignan , July 8, 2009. [Agencies]

The 37-year-old Texan is second overall, but about to face his toughest test in this year's Tour as the grueling three-week race arrives in the Pyrenees mountains.

"That's my question mark, that's your question mark, that's everybody's question mark," Armstrong said. "But we don't have to wait long until we'll find out, that's the good thing."

Armstrong is again eliciting fear among his rivals after an astute move that earned valuable time over his rival and teammate Alberto Contador, plus an impressive show at the team time trial.

He couldn't be in a better position before heading into the mountains. But a lurch Friday in Arcalis, Andorra - the finish of the first of three Pyrenean stages - would bring him back down to earth.

Armstrong didn't take any risks during Wednesday's fifth stage with the mountains looming. Thomas Voeckler of France won the 122-mile ride along a windy Mediterranean Sea from Le Cap d'Agde to Perpignan after a long breakaway.

"I think I'll be good," he said.

With defending champion Carlos Sastre 2:44 back, two-time runner-up Cadel Evans lagging 2:59 behind and Denis Menchov 3:52 back, the Tour could come down to Armstrong and Contador.

The Spaniard is third overall, 19 seconds behind Armstrong. Former Tour runner-up Andreas Kloeden is fourth, 23 seconds back, and Levi Leipheimer of the United States is fifth, 31 seconds behind.

Contador, the 2007 Tour winner, will ride with the support of home fans in the coming days. The stage Thursday is a 112-mile trek in Spain between Gerona and Barcelona, scheduled a day before the big rendezvous in Arcalis.

To Contador's advantage, he's the best climber in the world and his legs are 11 years younger than Armstrong's. He's rejoicing that the race is finally reaching his usual playground.

"I can't wait to get to the mountains because it's my territory. The sensations are good, but I always like to confirm them," he said.

Because he's behind Armstrong, Contador probably won't get carte blanche from Astana team manager Johan Bruyneel and won't be allowed to attack the Texan if he responds well in the climbs.

Armstrong, who underwent a doping test Wednesday, seems perfectly aware that Contador will be physically stronger than him in the mountains. But the seasoned veteran believes his mental resources will prevail.

"Strength does not come from physical capacity. It comes from an indomitable will," Armstrong said on his Tweeter account, quoting Mahatma Gandhi.