Portugal's Rui Costa claimed his second win of the 100th Tour de France after soloing to victory in the 204.5km 19th stage.
Movistar rider Costa shot out of a chasing peloton on the fifth and final climb to catch stage leader Pierre Rolland (Europcar) and went on to cross the finish line 47secs ahead of German veteran Andreas Kloden (RadioShack).
Chris Froome finished 25th after a relatively smooth ride in which his rivals showed little sign of wanting to attack him.
Team Sky leader Froome came over the finish line just under nine minutes in arrears but with his 5min 11sec overall lead over Spanish rival Albeto Contador intact.
On the penltimate day of climbing on the race, Contador's Saxo team tried several times to test Team Sky and Froome by upping the pace on the last two of the stage's five climbs.
But while their efforts helped drop several of Froome's teammates, the Kenyan-born Briton finished on the wheel of Australian teammate Richie Porte, who had been briefly left trailing on the final climb.
Ahead of Saturday's final day in the Alps, the 125 km 19th stage from Annecy to the summit of Annecy-Semnoz, Froome looks virtually assured of succeeding compatriot and teammate Bradley Wiggins as the race champion.
Contador's biggest worry may now be protecting his runner's up place from Colombian climbing specialist Nairo Quintana, who is third overall at .