Challengers to Tour de France leader Bradley Wiggins left it late to launch an attack on stage 17 in the Pyrenees.
The cyclist is seeking to become the first British winner of the yellow jersey in Paris on Sunday and began the day with a lead of two minutes five seconds over Team Sky colleague Chris Froome, with Italian Vincenzo Nibali 18 seconds further adrift.
No other rider was within five minutes of the triple Olympic champion at the start of the 143.5-kilometre route from Bagneres-de-Luchon to Peyragudes.
Nibali's Liquigas-Cannondale team were prominent, but Wiggins' Team Sky were present in numbers at the summit of the day's penultimate climb, the 11.7km hors categorie (beyond category) Port de Bales.
It left Nibali - and anyone else seeking to overhaul Wiggins, who was wearing the maillot jaune for a 10th day - needing to make their move on the descent and the day's final ascent, the 15.4km climb to Peyragudes.
The next opportunity for time gains after stage 17 is Saturday's penultimate day time-trial, with Wiggins imperious in the discipline.