Chris Froome took another big step towards a third Tour de France title when he dropped his main rivals in the finale of the 17th stage, a 184-km mountain trek won by Russian Ilnur Zakarin on Wednesday.
Froome (Team Sky) attacked inside the last two km in the last ascent, a punishing 10.4-km climb at an average gradient of 8.4 percent and Dutchman Bauke Mollema, second overall, as well as last year's runner-up Nairo Quintana, could not follow.
The Briton finished on the wheel of former team mate Richie Porte (BMC), the Australian emerging as a potential podium finisher in Paris.
Froome leads Mollema (Trek-Segafredo) by 2:27 and compatriot Adam Yates by 2:53, according to provisional results.