France hooker Dimitri Szarzewski has been surprised by Wales' good form during the RBS Six Nations.
Under the guidance of new coach Warren Gatland, Wales have won four games in a row and require victory over France in Cardiff on Saturday to complete the Grand Slam.
And Szarzewski admits he was not expecting Wales to be such a force following their dismal World Cup campaign last autumn when they exited at the group stage after losing to Fiji.
"They are starting to enjoy themselves after the problems they had during the World Cup," said Szarzewski.
"I saw their opening match against England (Wales won 26-19) and the result was a bit surprising.
"But they look to have a strong all-round team now and their pack is back to a good level.
"We are also evolving. We are pleased with where we are compared to the start of the tournament.
"But now we need to make an even bigger step up against the Welsh. There is going to be a lot of intensity, having seen the importance of this match."
France need to win by at least 20 points at the Millennium Stadium to retain the Six Nations title, which they won in both 2006 and 2007.
Les Bleus have won three out of four this year, most recently a laboured 25-13 success over Italy last Sunday. Their only defeat came in Paris against England on February 23.
"It was good to get back to winning ways against the Italians because the defeat to England had got into our heads," noted Szarzewski.
"Winning the match against Wales is the most important thing. Then we will see what happens.
"But we can't make any mistakes if that is going to happen. We will have to see how the match develops and if there is the possibility of winning by 20 points, all the better."
Szarzewski is confident that France's lineout - an area of concern against Italy - will improve in Cardiff.
"It's true that we are not having the most success in the lineout at the moment," he added.
"We have looked at the video and it's clear that Sergio Parisse (Italy's No.8) had analysed our lineout very well.
"We weren't getting the timing right with the lifting and that all led to us losing the ball. And with all the pressure, it did not help with our execution.
"But we have looked why it did not work and we have worked on them in training."