REIMS: Two-time Tour de France winner Alberto Contador is most feared when his back is against the wall.

And that is the position the Spaniard finds himself in as this year's race approaches the Vosges mountains for three stages from Saturday.

Contador (Tinkoff-Saxo) was not alone in facing the task of having to reel in the strong lead being enjoyed by the Tour’s Italian race leader Vincenzo Nibali (Astana) going into Friday’s flatter 234.5km seventh stage from Epernay to Nancy.

But as one of two main favourites for this year’s race with defending British champion Chris Froome (Sky) -  who abandoned on Wednesday –  all eyes are on Contador to ignite the fireworks to make inroads on Nibali’s lead before it's too late.

Contador, the 2007 and 2009 Tour winner, was the lowest-placed of the main contenders for overall victory this year in 19^thplace at 2 minutes 37 seconds to Nibali who won last year’s Giro d’Italia after placing third overall in the 2012 Tour.

“If we want to win, we have to attack. It’s not complicated,” said Contador’s team manager Bjarne Riis.

“It won’t be easy, but we are going to try. Alberto is a fighter.”

Contador’s Australian teammate, Michael Rogers, believes the Spaniard’s desire to win – in this case, the Tour for the first time since his return from a doping ban after testing positive for clenbuterol in the 2010 Tour – is a stand-out trait.

“That’s the difference between a real winner like Alberto who even if he is not in top condition still wants to win,” said Rogers whose role is to help Contador in the mountains.

“His mindset going into every race is to win which is relatively unique characteristic.”

Australian Richie Porte, a former teammate of Contador who is leading Sky after Froome’s withdrawal, expects the Spaniard to come out on the offensive in the Vosges.

“[Alberto] is a racer. I think Nibali is, too. But I don’t think Alberto is going to take this one lightly,” Porte said.

“I’m sure we’re going to see fireworks on the weekend.”

Such an all-out offensive is needed early to beat Nibali, says Marc Sergeant, manager of the team of Belgian Tour hope Jurgen Van den Broeck (Lotto-Belisol) who was sixth at 1 min 45 secs to Nibali going to Friday’s stage.

“With that much time [that Nibali has], it's going to take some big actions,” Sergeant said.

“Knowing Contador, he can do that. If you want to win the Tour, you have to put pressure on the Nibali and the team.

"If you wait to the Pyrenees, it's too late.”

Taking back time on Nibali overall is not only Contador’s task to embrace though.

After German Andre Greipel (Lotto-Belisol) won Thursday’s 194km sixth stage from Arras to Reims in a sprint, Nibali led his Danish teammate Jacob Fuglsang by 2 secs and Slovakian Peter Sagan (Cannondale) by 44 secs.

With Contador, Porte and Van den Broeck, other overall contenders chasing Nibali were Poland’s Michal Kwiatkowski (Omega Pharma-QuickStep), fourth at 50s; American Andrew Talansky (Garmin-Sharp), ninth at 2m 5s; Spain’s Alejandro Valverde (Tinkoff- Saxo), 10^th at 2m 11s; American Tejay van Garderen (BMC), 12th at same time; France’s Thibaut Pinot (FDJ), 15^th at 2m 25s; and Dutchman Bauke Mollema (Belkin), 18^th at 2m 27s.

The Vosges offer ample opportunity to challenge Nibali before the Alps and Pyrenees after which the last time deciding leg is the 54km stage 20 time trial from Bergerac to Perigueux which for a number of hopefuls will not be to their advantage.

Saturday’s 161km eighth stage from Tomblaine to Gerardmer is a taster with two second category climbs inside the last 30km before a third category ascent to the finish that should see the top contenders shadow box in readiness for what is to come.

Sunday’s 170km ninth stage from Gerardmer to Mulhouse has six climbs, but with the last climb 43km from the finish, it is possibly too far away for a break to stay away.

Monday’s 10^th stage goes from Mulhouse to the summit of La Planche des Belles Filles, a 5.9km ascent at an 8.5 per cent gradient, but ending with a 20 per cent pitch.

But making the stage tougher is that it will be preceded by six categorised climbs.

However, as Rogers says - perhaps to keep a veil of uncertainty over where and when Contador will strike in the coming days - it isn’t always on the hardest courses that the most potent and significant attacks are made in a bike race.

Asked if stages like Saturday’s to Gerardmer that may be deemed easier than the other two had potential for an unexpected move, Rogers said: “They can be stages - ‘GC’ [general classification]-wise - more demanding than the actual big stages on paper that everyone is waiting for the day, and not expecting anything to happen on.Then the coin turns.”

In whose favour the coin will land by the time the Vosges have been passed is anyone's guess.