France coach Bernard Laporte blamed exhaustion for what he admitted was a "nightmare" late collapse in Saturday's 43-31 RBS 6 Nations victory over Ireland.
Les Bleus, who suffered a shock 20-16 defeat in Scotland on the opening weekend, roared to a 43-3 lead after 47 minutes of play following tries from Aurelien Rougerie, Olivier Magne, Cedric Heymans (2) and David Marty (2).
But Ireland made an impressive comeback, scoring four touchdowns in less than 15 minutes and clinching 28 unanswered points before running out of steam.
"The answer to what happened is simple," said Laporte. "We were exhausted.
"We existed physically for 50 minutes and then collapsed in the last 30.
"Against the talented Irish trio of Brian O'Driscoll, Gordon D'Arcy and Ronan O'Gara we struggled a lot and were unable to keep up the pace - not to mention a bad kicking game from us which did not ease things."
Despite Ireland's comeback Laporte congratulated his players for their performance.
"We are happy with our first 50 minutes which reassured us," he added.
"Scoring over 40 points in 50 minutes against a rugby nation of Ireland's calibre is quite rare. Of course, the remainder of the match was disappointing because we gave a lot of space to the Irish.
"Watching them score so many tries in such a short period of time was a nightmare - I felt I was in a film."
Laporte refuted Ireland coach Eddie O'Sullivan's comments that Les Bleus had not played well throughout the match and that his own side had produced most of the rugby.
"I think he is right on the last 30 minutes, yes," said Laporte. "We simply did not get the ball.
"But before that, we still scored quite a few tries."
Italy Under-20s held off a late Samoa blitz to retain their place in the World Rugby U20 Championship on Saturday and head coach Alessandro Troncon believes the experience will have served as a valuable lesson for his young troops.