Franck Fife / AFP - Getty Images

Overall Tour de France leader Lance Armstrong keeps an eye on rival Jan Ullrich, left, as Ivan Basso keeps pace during the 15th stage of the Tour on Sunday.

Hincapie and Oscar Pereiro, having shaken off the rest of their group, fought for the victory alone on the final and hardest climb to the Pla d’Adet ski station above the Pyrenean town of Saint-Lary-Soulan.

There, Hincapie beat the Spaniard with a sprint finish, shaking his head in disbelief as he crossed the line.

Hincapie is the only one of Armstrong’s eight teammates to have been with the Texan for all of his six Tour victories. The last time the Tour visited Pla d’Adet, in 2001, Armstrong won — on the way to his third Tour title.

“To win a stage in the Tour de France is special, but to win a stage like this which is arguably the hardest stage of the Tour is a big, big accomplishment. He deserves it,” Armstrong said.

Hincapie’s time was 6 hours, 6 minutes, 38 seconds. Pereiro was 6 seconds back. Three other members of their breakaway group placed third, fourth and fifth.

Behind them, Armstrong again held off his strongest rivals — Italian Ivan Basso and German Jan Ullrich.

Basso was sixth, with Armstrong right behind. They both finished 5 minutes and 4 seconds behind Hincapie. The effort moved Basso up to second in the overall standings, but he still trails Armstrong by 2:46.

Ullrich struggled on the final climb, placing ninth. His overall deficit to Armstrong grew to 5:58.

Mickael Rasmussen of Denmark, who had been second overall, 1:41 back, fell to third, now 3:09 behind Armstrong. Hincapie is 18th overall.

Armstrong said his lead is “more secure,” but that hard racing lies ahead in the last week of the three-week event.

“You never know, you go to a village and take a turn too fast and break your collarbone — Tour de France over. So you have to be realistic,” Armstrong said. “We have a week to go and a lot of things can get in the way.”

Crowds are among the potential risks. Some fans ran dangerously alongside the riders up Sunday’s climbs. One was knocked down by a motorbike carrying a television cameraman who was filming the race. Race organizers said they had no word on whether the fan was hurt.

The riders passed a monument marking the spot where Fabio Casartelli, Armstrong’s former teammate, fell and died on July 18, 1995.

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Casartelli, the 1992 Olympic road race champion, suffered head injuries in the crash after completing the difficult Col du Portet d’Aspet climb. He was traveling at about 53 mph.

“The feeling hasn’t changed over the years,” Armstrong said after meeting at the start with Casartelli’s parents, widow and 10-year-old son at his Discovery Channel team bus.

“I still get a tear in my eye and still get goose bumps when I pass that incredibly beautiful monument.”