Jacques Brunel was at a loss to explain how France let victory slip against Wales as they saw a 16-point lead overhauled in their Guinness Six Nations opener in Paris.
Les Bleus looked on course for victory after first-half tries for Louis Picamoles and Yoann Huget, along with six points from the boot of Camille Lopez.
However a try early in the second period from Tomos Williams, followed by two opportunistic scores from George North, after a handling error by Yoann Huget and then an intercepted Sébastien Vahaamahina pass, allowed Wales to turn it around for a 24-19 victory.
A year on from seeing Johnny Sexton deny them in the final seconds at the Stade de France, it was another heartbreaking loss for France, with Brunel frustrated at the way the game got away from his side.
He said: “It’s difficult to explain. It’s not a lack of fighting spirit, it’s a lack of control in important moments.
“It’s difficult to explain how and why an experienced player like Yoann Huget lets a ball slip out of his hands after running back 30 metres. It’s never happened to him and probably never will happen again. It’s something you can’t explain.
“It’s a disappointment because we were very committed, we did interesting things, especially in the first half. Even if we didn’t control everything, we put this Welsh team under pressure. They have a good defence, which they showed in the second half.
“It’s not the mental frame of mind. We were fully committed until the end. It was a problem of control.”
The loss leaves France with a huge challenge ahead of them as they travel to England in round two, having last won at Twickenham in the Championship in 2006.
But despite the frustration at the defeat, Brunel was keen to highlight some positives, particularly from a dominant first half.
He added: “Of course I’ll take some positives because it feels like on the whole, we produced some good passages, against the best defence, at least in Europe, under pressure. I think we put them under more pressure than they did us.
“But disappointment is the main feeling. Again we will have to question everything and start again against a very good team.
“We have a big challenge in a week’s time.”