Australia's Cadel Evans has edged closer to the overall lead as he seeks a historic Tour de France victory.
Evans gained 27 seconds on Thomas Voeckler, who retained the yellow jersey after Wednesday's 17th stage was won by Norway's Edvald Boasson Hagen.
VIDEO: Cadel Evans post stage 17
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Race favourite Evans finished in a group that included defending champion Alberto Contador and the Schleck brothers 4min 26sec back.
The favourite is now just 1min 18sec behind Voeckler in second spot ahead of two more days in the Alps.
Anticipation that Evans will become the first Australian to win the famous race grows with each day he keeps his advantage of nearly two minutes over Contador.
"With shadows and stuff it was real hard to see," Evans said.
"Voeckler ran off the road in front of me - twice I think. It makes you take things more cautiously. You don't ever want to lose time to anyone.
"I've got a good advantage over Alberto now, but Alberto has shown in years gone by what he can do when he's really at his top."
Defending champion Contador made repeated attempts to pull away from his rivals, but was caught on each occasion.
Boasson Hagen completed the 179 km across the Alps from Gap to the Italian town of Pinerolo in 4hr 18min.
Bauke Mollema of the Netherlands was second, 40 seconds back, with Sandy Casar of France winning the sprint for third.
It was the second victory for Sky rider Boasson Hagen and the fourth for Norway in this year's race.
It was also a form of revenge, after he was beaten into second by his compatriot Thor Hushovd on Tuesday.
"It was very difficult yesterday, and today I was able to do better," said Boasson Hagen. "I didn't want to lose this race today."
Mollema's second placing came as Frenchman Jonathan Hivert crashed on the perilous final descent of the Pramartino before getting back on his bike to finish ninth.
Voeckler veered off the course at one point during the last descent, but didn't crash.
"It's a pity, because I saw that Contador, Evans and the Schlecks finished together. If I'd taken fewer risks, I would have finished with them," he said.
