Andy Schleck believes his battle with Alberto Contador for this year's Tour de France crown will be decided during Thursday's climb up Col du Tourmalet.
The Spaniard holds an eight-second lead over Schleck, having seized the advantage when his rival suffered a mechanical failure in Monday's stage.
"I believe the Tour will be decided on the Tourmalet - the first guy up there will also win the Tour," he said.
Wednesday is a rest day before the riders take on the 174km 17th stage.
Friday's stage returns to the flat before Saturday's individual time trial - the penultimate stage before the short ride into Paris on Sunday.
Both contenders are believed to be of equal calibre in the mountains but defending champion Contador is widely regarded as a considerably better time-trialist. But the Spanish Astana rider said it would be simplistic to dismiss his Saxo Bank rival during Saturday's stage.
"I fear Schleck in the time trial simply because he's a great rider - he won the Luxembourg time trial championship, which proves he's improved in the discipline," said the 27-year-old. "What's for certain is that there's going to be a great battle between us."
Contador had earlier issued an apology to the Luxembourg rider for capitalising on the slipped-chain incident during the closing stages on Monday and seizing the race lead.
The duo subsequently embraced at the finish on Tuesday.
Contador stated: "We are big friends and that won't change because of what happened."
Schleck added: "Sometimes in a race things like that happen but now we have settled things with each other."
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