Despite their being underdogs for the clash, Williams said that France are capable of delivering a major upset.
"They can shock us, as they've done in past World Cups," Williams said.
"You can play against one side one week and then you play against them a couple of weeks later and they're a different team. Past form means nothing.
"Their scrum is up there with the best in the world, their lineout is not too bad either and their backs are unpredictable."
Former Toulon player Williams, who won his first All Blacks cap in 2010, has scored four tries in 13 appearances.