Les Bleus responded from defeat to Tonga with a 19-12 quarter-final victory over England at Eden Park in Auckland on Saturday, while Wales advanced courtesy of a 22-10 defeat of Ireland in Wellington.
Wales' World Cup has featured a narrow defeat to South Africa before wins over Samoa, Namibia, Fiji and Ireland.
And their form has not gone unnoticed.
Lievremont said: "They came out of the hardest pool, having lost to South Africa, when they deserved to win - I thought to myself they wouldn't recover from that.
"They play a great style of rugby, more complete than what England showed in the tournament. The way they controlled Ireland was impressive.
"Fundamentally I think they're playing the same rugby of three years ago when they won the Grand Slam."
Wales finished fourth in the RBS 6 Nations and were beaten 28-9 by France in Paris in March.
France have lost only two of their last 11 clashes, on the two occasions when Wales won the Grand Slam - in 2005 and 2008.
"Wales haven't always been the most consistent side," Lievremont added.
"The fact they're showing this consistency is encouraging for them.
"Warren Gatland has managed to freshen up his squad with some very talented players.
"They have mobile, brave forwards. The way they stood up to Ireland was impressive and there is a great understanding among the backs and a lot of speed.
"We're coming up against Jamie Roberts, the best centre since the start of the tournament without a doubt."
France scrum-half Dimitri Yachvili also knows the size of the task facing his side.
He said: "We have a big clash next Saturday. Wales are a very good team.
"They look very fit, very well in their game plan, so it's going to be very hard."
Yachvili attributed the difference which allowed Jekyll and Hyde France to beat England to a greater team unity.
He added: "We knew if we wanted to beat England we had to work together. All the week we said we had to put very big pressure, we had to be very hard in the tackle, we had to never give up and we didn't gave up.
"Last week we didn't show team spirit. Last week was a game to forget. So the team spirit was very important."
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