Thomas Tuchel blamed over-confidence as the catalyst of Paris Saint-Germain's shock Coupe de la Ligue exit at the hands of Guingamp.
Holders PSG succumbed to Marcus Thuram's 93rd-minute spot-kick after giving away three penalties in a dramatic 2-1 quarter-final defeat at Parc des Princes on Wednesday.
An action-packed second half saw Thuram blaze over from 12 yards moments prior to Neymar's opener, before Juan Bernat's tangle with Marcus Coco enabled Yeni N'Gbakoto to equalise by sending Alphonse Areola the wrong way.
Young Guingamp striker Thuram then overcame his earlier anguish to remove PSG's grip on the trophy, the Ligue 1 champions having won the competition in each of the previous five seasons.
"I do not know if it's deserved, we had a lot of chances," Tuchel said of the loss in an interview with Canal+.
"We played honestly with too much confidence. It's hard to lose this match with three penalties. It's a bit weird.
"The second seems questionable. There was nothing [there], it is a [normal] contact between the two players. They entered our box three times and won three penalties.
"We didn't play with the necessary hunger. We lost the possibility of winning a trophy tonight.
"But in each defeat, there are things you can learn. It's hard, but it's necessary to keep growing, I hope it's just an accident.
"We have to play with more consistency, we didn't put the right ingredients in. We were too relaxed."
Thomas Meunier and Thilo Kehrer were the other PSG players to concede spot-kicks as Tuchel's men, 13 points clear in Ligue 1, proved the architects of their second defeat in all competitions in 2018-19.
Guingamp head coach Jocelyn Gourvennec was left struggling to make sense of the triumph, having witnessed three goals and three penalties in the final 30 minutes.
"We never know what to expect here, they often put up heavy scores and very quickly," Gourvennec said.
"With Guingamp or [my former club] Bordeaux, it's always been complicated here for me. I don't really know what happened. We managed to get them into trouble."