Scott Johnson believes that France will present a ''huge challenge'' to Wales' RBS 6 Nations title ambitions in Paris next weekend.
And Wales assistant coach Johnson also anticipates a more open game from the French following scrum-half Dimitri Yachvili's goalkicking masterclass during the 18-17 victory over England.
''I think they will open up a bit more and try to play a faster game,'' said Johnson. ''The pressure is off them, now they have beaten England.
''The French were under the cosh in the first-half at Twickenham, and nobody gave them a prayer at half-time. But they clung on, when a lesser side would have folded, and they stole the game in the end.
''The French may be renowned for their attacking qualities, but they have one of the best defences in the world game. Their lineout is very, very strong, their scrum is solid and technically they are very efficient.
''They do the basics as well as any team in the world, and they are going to present us with a huge challenge in Paris.''
Wales coach Mike Ruddock is due to announce his starting line-up for the game on Tuesday evening.
England Under-18 head coach John Fletcher insists his young side will be better for the experience after beating Italy in the bronze final to round out their 2015 Rugby Europe U18 Championship campaign in style.