France coach Bernard Laporte has warned his players to beware of a Wales backlash when the two teams meet in a crunch Six Nations Championship encounter in Cardiff on Saturday.

Les Bleus can all but guarantee their third Six Nations title in five years with a victory at Cardiff’s Millennium Stadium, as long as Ireland do not notch up a cricket score at Twickenham.

If France fail to win however, Ireland can secure the title with a win over England, but the world champions will be as determined as Wales not to finish their campaign on a sour note.

Standing in the way of the French is a Wales side who have struggled on and off the pitch in recent months.

They have had to withstand the departure of coach Mike Ruddock while their performances in their opening four games have been a far cry from the swashbuckling, attacking displays of last year’s grand slam campaign.

Their only points in this season’s tournament have come from a win against a Scotland side reduced to 14 men for the majority of the match and a draw against likely wooden-spoon recipients Italy last time out.

But Laporte believes this weekend’s contest could be the toughest so far for his team. "If we want to win the Six Nation’s tournament, we have to put in just as big an effort as we have done so far," he said.

"It will be a difficult game because Wales have not had a great tournament and they would like to finish well at home. We have to be at 100 per cent if we want to win."

Laporte has made just one change to the side that crushed England 31-6 in Paris last Sunday, Bourgoin’s Julien Bonnaire promoted from the bench into the back row in place of veteran Olivier Magne.

Magne takes his place among the replacements while Bonnaire will team up with Thomas Lievremont and Yannick Nyanga at the base of the scrum.

France, who came into the tournament as favourites following their superb results in the autumn internationals, have not been at their best but have shown good powers of recovery since their surprise opening weekend defeat to Scotland.

They have won three straight games - against Ireland, Italy and England - to go top of the table on points difference over Ireland and Laporte has urged his side to finish the job against the Welsh.

"We are not pretentious but no-one has scored 43 points against Ireland," he added. "We have lost one but we have realised our mistakes and that is good for future.

"If we win against Wales, we win the tournament so our players’ motivation is real.

"It is all about us now. As long as we are on top form, we don’t have to think about our opponent."