Les Bleus travel to Wales knowing victory will all-but guarantee them their third title in five years and, while anything other than victory over last years Grand Slam winners will be viewed as a shock, Saracens star Castaignede insists he and his team-mates need to do more than just turn up to secure victory.

The job is not finished, he said. Fear is a necessary evil before the fight at Cardiff.

Bernard Laportes troops have recovered from their opening-day defeat in Scotland with victories over Ireland, Italy and England.

However, their form in those victories has been far from sparkling, with both Ireland and Italy threatening to take advantage of Jekyll-and-Hyde displays at the Stade de France.

England were dismissed with consummate ease last weekend, but some pundits felt the victory said far more about English frailty than about French strength.

Goal-kicking scrum-half Dimitri Yachvili returned to torment the world champions for the third straight season on Sunday and has kept his place in the starting XI ahead of rival Jean-Baptiste Elissalde.

He knows that putting one foot wrong against Wales could see him fall behind once again in the pecking order ahead of next years World Cup, but he welcomes the pressure both on him as an individual and the team.

It is important to have pressure, it helps you when you play against the great nations of rugby, he said.

Cardiff is another test for France even if Wales are not playing the same as last year.

Despite their unconvincing form, France are on the brink of breaking their try-scoring record in the competition, needing just two more to eclipse their previous best tally of 17.

Head coach Laporte believes this demonstrates his sides attacking prowess but has warned against complency in Cardiff.

We scored more tries than last year, it proves that France can attack, he said. We are first but we have not won yet. I am pleased with the team but I repeat, the game will be difficult for France. We know Wales and we have to be ourselves to win.

It was no surprise to hear those sentiments echoed by skipper Fabien Pelous, who came into this years tournament on the back of a nine-week ban.

After four weeks of training, you feel better and better, he said. There is one thing which has changed which is the fighting spirit in the squad. We have to win, it is the main objective for us.