BOURG-SAINT-MAURICE, France - Alberto Contador fought to retain the Tour de France lead and Lance Armstrong clung to second in Tuesday's 16th stage, which was won by Spanish rider Mikel Astarloza.
Contador and Armstrong finished in a group of race leaders behind Astarloza in the 159-kilometre ride through the Alps from the Swiss town of Martigny to Bourg-Saint-Maurice.
Contador, the 2007 Tour winner and pre-race favourite this year, said he struggled to fight off an attack led by brothers Andy and Frank Schleck of Luxembourg in the day's second big climb.
"We had expected (an attack) and I gave my maximum. I could resist but not without difficulty," Contador said. "I'm happy after this difficult day."
Astarloza, a 29-year-old rider on the Euskadi Euskaltel team, thrust his fists in the air and kissed his fingers as he crossed the line in four hours 14 minutes 20 seconds - six seconds before French riders Sandy Casar and Pierrick Fedrigo.
With about two kilometres to go, the Spaniard escaped three other breakaway riders with him and held on through the finish to collect his first Tour stage win.
"I was lucky to leave alone and finish alone," Astarloza said. "I'm a complete rider, but I'm not good at the sprint - so I have to attack from far away.
"This is the biggest day of my career."
Contador, Armstrong, fourth-place teammate Andreas Kloeden, and third-place Bradley Wiggins of Britain all crossed 59 seconds after Astarloza.
Overall, Contador leads Armstrong by 1:37. Wiggins is third, 1:46 back, while Kloeden is 2:17 behind and Andy Schleck is fifth, trailing by 2:26.
Victoria's Ryder Hesjedal, the lone Canadian in the race, is one of the Garmin-Sliptream riders supporting Wiggins. Hesjedal was 90th Tuesday and stands 66th overall.
Spanish star Carlos Sastre stands ninth overall for the Cervelo Test Team, whose principal owner is the Canadian Cervelo bike manufacturer. Sastre, who won last year's race, was 24th in Tuesday's stage.
Riders scaled the highest peak at the Tour this year, the snowcapped Grand-Saint-Bernard pass on the Swiss-Italian border - at 2,473 metres. Its sister, the Petit-Saint-Bernard pass on the Italian-French border, was the days other big climb, and each was at least 22 kilometres long.
Despite the two tough climbs, racers had a long 31-kilometre downhill to the finish - making it difficult to hold on to a time gap that might have been gained on the final climb. Downhills make it hard for breakaway riders to outpace the fast-moving pack.
The final descent was perilous: Jens Voigt of Germany crashed either from a bicycle malfunction or hitting a bump in the road - it was not immediately clear - and was taken to the hospital by ambulance.
"He lost consciousness for a while, but he should be OK," CSC team manager Bjarne Riis said. "For me, it's a good sign."
The Tour's medical staff said Voigt sustained a severe contusion on his face and right elbow, and was flown by helicopter to the hospital in the French city of Grenoble, where he was to undergo tests.
During the stage, an Astana team vehicle was stopped and searched by customs officials at the Swiss-French border, a team spokesman said, adding that nothing of concern was found.
Pope Benedict XVI sent greetings to Tour competitors and organizers on Tuesday as the pack passed close to the Alpine retreat of Les Combes, overlooking Mont Blanc, where the pontiff is staying.
Wednesday's stage features what some riders fear is the toughest Alpine trek this year - a 169.5-kilometre ride from Bourg-Saint-Maurice to Le Grand-Bornand featuring five tough climbs, and another downhill finish.
The Tour ends Sunday in Paris.
AP sportswriter Samuel Petrequin contributed to this report.