Bradley Wiggins of Britain mastered a last big test in the mountains to retain the yellow jersey on Thursday, while Alejandro Valverde of Spain won the 17th stage of the Tour de France.
After ascending the last huge climb, Wiggins said he sensed victory with just three racing days left. He's trying to become the first Briton to win cycling's biggest race.
Wiggins faces one last test - the individual time trial, his specialty - on Saturday.
Flat stages await on Friday and Sunday, which features the ride to the finish on the Champs-Elysees in Paris. Those stages aren't expected to alter the standings.
An 89-mile ride from Bagneres-de-Luchon to the ski station of Peyragudes on Thursday featured three hard climbs and an uphill finish.
Valverde, the Movistar leader who returned from a two-year doping ban this year, won his third Tour stage in a breakaway. Christopher Froome of Britain was second, and his Sky team leader Wiggins was third, both 19 seconds back.
Overall, Wiggins leads Froome in second by 2 minutes, 5 seconds, and Italy's Vincenzo Nibali trails in third, 2:41 back, after losing 18 seconds to them in the final ascent.
Valverde, with tears in his eyes in the winner's circle, had a rough start to the Tour with at least three crashes. He sensed Wiggins and Froome closing on him at the end of the stage.
"I went all out," said Valverde, who also won stages in the Tour Down Under and the Paris-Nice races this year. "When I saw there were only 700 meters left, I was really really happy".
One of Sky's dilemmas was exposed on Thursday: Froome entered the day clinging to an 18-second lead over Nibali, and he was looking for any chance to gain time on the Italian.
On the final ascent up the Peyragudes, Froome tried to gain time on Nibali, but also repeatedly spoke with Wiggins and gestured to him to come along.
"Chris encouraged me, saying 'Come on, come on,'" Wiggins said. "He's really strong ... he can win the Tour one day."
The 18th stage on Friday takes riders on a 137-mile trek from Blagnac to Brive-la-Gaillarde in central France.