Race favourite Cadel Evans remains in contention to take out the Tour de France despite falling more than 90 seconds behind new leader Carlos Sastre.
The Spaniard grabbed the yellow jersey from CSC team-mate Frank Schleck after kicking away on the final ascent of the 210km ride from Embrun to Alpe d'Huez to claim a convincing victory in the 17th stage of the Tour.
Sastre, 33, dropped the maillot jaune group 13km from the summit of the infamously steep Alpine climb, and none of the main contenders for victory was prepared to follow him.
Andy Schleck and Samuel Sanchez came in two minutes and three seconds behind Sastre, who took the second Tour de France stage victory of his career.
In the 25 previous summit finishes at Alpe d'Huez, the man wearing yellow on the podium has gone on to win the Tour 19 times.
But with the last of the mountain stages now behind him, Evans is confident of reducing the deficit in Saturday's 53km time trial from Saint Amand to Cerilly to regain the yellow jersey for the final ride into Paris.
"The time trial is the race of truth," Evans said.
Team CSC may now have to rethink its strategy, with Sastre 1:24 ahead of Frank Schleck in the general classification.
Frank Schleck was unable to put clear distance between himself and Evans, despite the best efforts of his younger brother Andy and unexpected help from Caisse d'Epargne's Alejandro Valverde.
Valverde repeatedly tried to pull Schleck away from Evans, but the Luxembourger was unable to produce the crucial kick that could have given him breathing space for the stage against the clock.
Schleck needed the sort of kick he produced two years ago on Alpe d'Huez, when he pulled away from Damiano Cunego in emphatic style.
Sastre has long been considered a brilliant but erratic climber in the Spanish tradition.
He was over a minute slower than Evans and Denis Menchov in the first time-trial at Cholet, which could make for a nail-biting finish if he maintains his 84-second advantage when the peloton reaches Cerilly.
Sastre was effusive in his praise for his team-mates, who again forced the pace.
"We have seen a great stage, and a team which worked perfectly," he told letour.fr.
"Without the support of Frank and Andy, none of this would have happened."
"We had to choose the right rhythm at the foot of the last climb, and accelerate later."
"Normally, a good climber is able to capitalise on this sort of situation, and that's what happened."
"I don't know if I have the crucial advantage, we'll see what happens in the time-trial on Saturday."
"I knew that for the time-trial, I had to win lots of time on Evans. So today was my only chance."
Bernhard Kohl, the revelation of this year's Tour, also remains in contention, sandwiched between Frank Schleck and Evans in third place.
The young Austrian from Gerolsteiner cemented top spot in the King of the Mountains competition, opening up a 45-point lead on Frank Schleck and Sastre, with the CSC duo expected to concentrate on the general classification.
The 210km stage was the most taxing day in the Tour so far, taking in three hors-categorie climbs in the high Alps.
Stefan Schumacher led over the Col du Galibier, but Peter Velits dropped the German on the long climb up the Col de la Croix de Fer, and Jerome Pineau joined the