EPERNAY, France (AFP) - Peter Sagan has earmarked Friday's 234.5km stage from Epernay to Nancy to land his first victory on this year's Tour de France.

The 24-year-old Slovak has been the most consistent rider on the Tour so far and holds the points leader's green jersey.

But after twice finishing second, three times fourth and once fifth on the six stages, he cut a frustrated figure at his inability to turn that regularity into a victory.

But Friday's stage promises to be his best chance yet, with two short tough climbs in the final 20km.

The second ends just 5.5km from home and that after a brutal 1.3km ascent at an average gradient of 7.9 per cent.

It means pure and burly sprinters such as Germans Marcel Kittel and Andre Greipel, who have won four sprint finishes between them, could get dropped on the climb, leaving a better all-rounder like Sagan to strike.

"If I look back to the stages we've done, I have two different feelings. I have a good advantage in the green points classification, I finished always in the front," he said.

"On the other side, this is not my first Tour de France, it's the third experience, and my aim is to do better and improve year by year.

"I had the chance to take the yellow jersey and I always get close to winning. Even (Thursday) I wanted to sprint but I had no luck.

"It's a little frustrating, maybe sometimes I ask too much to myself. But now I just want to concentrate and to try again."

Sagan crashed for the second day in a row on Thursday, to add to his general dark mood.

"The most important thing is that I have nothing broken. Two crashes in two days are not something that make me happy, but I'm OK," said the Cannondale team leader.

"I hope to absorb the bruises I have on my body as soon as possible."

The finale may not suit Kittel, who stands at 1.88m and weighs 82kg, but he has not ruled himself out of the final sprint, despite not managing to get involved in Thursday's run-in.

Having won all three bunch sprints before then, rumours of his powers had been greatly exaggerated, according to the 26-year-old Giant-Shimano rider.

He wrote on Twitter: "Who ever said we're unbeatable, you're wrong as you saw today. But we know the mistakes we did & we'll be back soon. We lose & win together!"

As for Greipel, he had been out of form until Thursday's sprint finish, which he won, with just one sixth-placed finish before that.

His victory came after Kittel dropped out of the reckoning with more than a kilometre still to ride, but Greipel insisted his victory was down to him being in the right position rather than Kittel being absent.

"I'm not looking at Kittel, I don't know what happened with him. I don't need to hide, I'm still one of the fastest in the bunch. I just need to be there at the right time in the right place," said the 31-year-old Lotto-Belisol rider.

Meanwhile, race leader Vincenzo Nibali is preparing himself for the inevitable attacks he will face once the Tour reaches the Voges.

As soon as Saturday's 161km run from Tomblaine to Gerardmer reaches its bumpy finish, that's where the attacks are likely to begin.

With a complicated and chaotic first week behind them, Nibali is sitting pretty on a lead of more than two minutes on almost all his GC rivals.

And the 29-year-old Sicilian says he's been taking strength from wearing the yellow jersey.

"For sure the jersey gives me great energy but at the moment I'm just trying to ride in the best way I can. The yellow jersey is something extra," he said.