Plateau De Beille, France ? Lance Armstrong was so far ahead and so relaxed after a grueling final climb Friday that he even had time to zip up the bright yellow jersey worn by the leader of the Tour de France.

A fourth straight title now seems almost as easy to secure.

Overall leader Lance Armstrong, center, in action with Christophe Moreau of France, left, and U.S. Postal Service teammate Jose Luis Rubiera, of Spain, right, during the 12th stage of the Tour de France. Armstrong more than doubled his overall lead during Friday's stage between Lannemezan and Plateau de Beille, southwestern France.

Continuing the amazing run of mountain wins he began when he returned from cancer to take his first title in 1999, Armstrong sprinted ahead of his rivals in the 12th stage and more than doubled his overall race lead.

But the Texan wasn’t claiming victory yet.

“I don’t celebrate a victory before the final lap on the Champs-Elysees,” he said. “One bad day, and you can lose everything.”

Four more mountain stages, two of them exceptionally difficult, still await riders. Yet it was hard to see how anything, barring illness or injury, could prevent Armstrong from keeping the yellow jersey all the way to the July 28 finish in Paris.

His rivals are far behind. Spain’s Joseba Beloki, Armstrong’s biggest challenger, trailed by nearly 21â2 minutes in the race standings after Friday’s stage in the Pyrenees. He was unlikely to improve his performance enough to stop Armstrong.

As he pedaled in the last climb to the Plateau de Beille, the U.S. Postal Service rider reached down to zip up his yellow jersey, which had been open to below the chest for much of the hot, sunny stage.

“I know this climb very well. It’s the nearest mountain pass to my home,” said Armstrong, who spends much of the year in Gerona, Spain. He clocked 6 hours and 29 seconds in the 123.69-mile stretch that began in Lannemezan.

Armstrong has held the yellow jersey since Thursday, when he won the Tour’s opening mountain leg.

That victory ended speculation, raised by his second-place showing in Monday’s time trial, that Armstrong was weaker this year. Friday’s win confirmed that he’s likely to take a fourth title.

The record is five. Four riders Jacques Anquetil and Bernard Hinault of France, Eddy Merckx of Belgium, and Spain’s Miguel Indurain have taken the title five times, and only Indurain won all five consecutively.

Armstrong won his first title less than three years after being diagnosed with advanced testicular cancer that had spread to his lungs and brain. He was given a 40 percent chance of survival, and underwent brain surgery and chemotherapy.

Already a world-class cyclist before he fell ill in 1996, Armstrong blew his competitors away when he returned to the Tour in 1999 after making a full recovery, and repeated a year later.

Last year, four stage victories were enough to seal the title for Armstrong, who established a whopping lead of 6:44 over his archrival, Jan Ullrich. The German, who is absent from this year’s Tour because of injury, was so thoroughly dominated that he acknowledged defeat with a whole week of racing to go.

At the time, Armstrong said he felt at his best level yet. There were no weak moments, such as the one he experienced at the 2000 Tour when he lost power in the last major mountain stage.

Yet before the start of this year’s race, the 30-year-old Armstrong said he felt stronger even than in 2001.

He will have another chance to prove it when the race heads to Mont Ventoux in the southern Vaucluse region on Sunday.

“I regard it as the hardest climb this year,” Armstrong said.

Two years ago, he could have won at Mont Ventoux, but pulled back in the finishing stretch to let Marco Pantani win, calling the decision a “gift” to the charismatic Italian. Pantani said he felt insulted.

“If I’m in front, I won’t make the same mistake again,” Armstrong said Friday.