Briton extends his lead over nearest non-Team Sky rider Nibali.
Bradley Wiggins closes in on yellow jersey as Valverde wins
Bradley Wiggins starts today's 18th stage of the Tour de France feeling for the first time that overall victory is his.
Wiggins came over the finish line of yesterday's 143.5 km stage between Bagneres-de-Luchon and Peyragudes on the wheel of his teammate Chris Froome, 18 seconds behind stage winner Alejandro Valverde of Spain.
And Wiggins said: "It's the first time I've felt maybe I've won the Tour today. That was an incredible feeling, to go over the last summit.
"All the way up the last climb it was like, tears in my eyes."
The 19th and penultimate stage tomorrow is a 53.5km time trial in which Wiggins and Froome, who were first and second on the stage nine time trial, are expected to excel and the race finishes in Paris on Sunday.
Wiggins began yesterday's stage with a lead of two minutes five seconds over Sky teammate Froome, with Vincenzo Nibali 18 seconds further adrift.
But Wiggins, with able support from Froome, distanced Nibali on the finishing ascent as the Italian fell further behind to face a deficit of two minutes 41 seconds with three days' racing remaining.
Froome was seen imploring Wiggins to stay with him in the finale, with Nibali struggling.
"We were talking about Nibali," said Wiggins. "We knew he was on his limit. The moment we crossed the Peyresourde, I allowed myself to drift and that was the first time I thought maybe I've won the Tour.
"All the way up that last climb my concentration had gone, everything about performance had gone. Chris was egging me on to take more time."
Wiggins added: "The minute we went over the Peyresourde, I pretty much knew that was the climbing done for the Tour and that was an incredible feeling. That's where everyone said I was at my weakest, in the mountains."
The British pair had led a frantic chase of Valverde on yesterday's fifth and last climb but Valverde, who had broken away from an early escape group, dug deep to hold them off.
Valverde, who only returned to racing in January after serving a two-year doping ban, had started the race with high hopes of aiming for a top three finish in the race.
But after hitting the tarmac several times early in the race, and seeing his team decimated by other crashes, the Spaniard's objective became a stage win. Having held a lead of 2:35 on the yellow jersey's group with the final 15 km climb to negotiate, his relief was all the more pronounced at the finish where he knew he was under threat by Froome and Wiggins.
"I knew they were behind me, I tried to go faster and so when I saw there was only one kilometre to go I was very happy," said Valverde after what was his fourth Tour stage win but first since 2008.
"It's a big victory for me and my team. It's been a very difficult Tour for me, with all the crashes and drama we've been through."
Cadel Evans, the defending Tour champion who lost nearly five minutes to Wiggins on Wednesday's 16th stage to drop to seventh overallin the standings, lost more time after struggling to hold the pace inside the final few kilometres of the stage.
It means Wiggins will go into today's 18th stage from Blagnac to Brive-La-Gaillarde, a sprinter-friendly stage which is unlikely to host a yellow jersey battle, with his lead intact.
Nibali lost 10 seconds to Jurgen Van den Broeck of Lotto, but the Italian remains third overall with a three-minute cushion on the Belgian, who is fourth.
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