France led 12-9 against the United States in Pool C of the World Cup with just 13 minutes remaining in Kobe City.
USA goal-kicker A J MacGinty had knocked over his third successful penalty to raise hopes of a massive upset.
But a much-changed French team from that which had pipped Argentina in their opening group match managed to find another gear with centre Gael Fickou, scrum-half substitute Baptiste Serin and prop Jefferson Poirot crossing the whitewash during a late 19-point whirlwind to secure a bonus point.
It ended 33-9 in France's favour as they moved past Argentina and into second in Pool C, a point behind England.
England face Argentina in a huge clash in Tokyo on Saturday with victory for Eddie Jones' team setting up a climax with France, who also face Tonga, to decide the winner of the group.
If it goes to seeding, England will emerge as victors with France facing Pool D favourites Wales in the quarter-finals on October 20.
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