Spain coach Luis Enrique blamed a "total loss of control" during a five-minute second-half period for his team's shock 2-1 defeat by Japan on Thursday.
Despite the defeat, Spain joined their opponents in the last 16 of the World Cup by virtue of a better goal difference than Germany, who finished third in Group E on four points following a 4-2 win over Costa Rica.
La Roja, among the favourites to win the tournament, would have been eliminated if Costa Rica had held on to beat Germany.
Alvaro Morata sent Spain in front early on but two strikes in four minutes from Japan at the start of the second half turned the game on its head.
"[It was] five minutes of total lack of control, of panic, even," said Luis Enrique.
"They scored two goals against us, and if they had needed to score two more, then they would have scored them too, I'm sure.
"This is a World Cup and when a team like Japan does not have anything to lose, well, they decide to risk it all and flew past us like they were aeroplanes.
"The situation was under control once Japan decided to recover their previous position on the pitch and shut up shop at the back."
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Ritsu Doan netted the equaliser for Japan in the 48th minute before Ao Tanaka bundled home an extremely controversial second.
The ball appeared to go out of play before Kaoru Mitoma crossed the ball to him, but after a long VAR check, officials granted the goal.
"I have seen a photo that must have been tampered with, it cannot be that this photo is real. It has to be manipulated," said Luis Enrique.
"I felt that something fishy was going on when the VAR took as much time as it did to decide ... I have nothing to say.
"Luckily the team only goes into collapse mode once every four years, otherwise I wouldn't be able to cope."
Spain will face Morocco in the last 16 after the defeat and Luis Enrique believes his team did not deserve to finish as group winners.
"Japan go through first and it's deserved because they beat Germany and Spain," he said the coach.
"The mourning and the pain, we'll go through that tonight, there's nothing to celebrate.
"We have gone through second, yes, but this has to serve as a warning to be aware that this is going to happen.
"If against Morocco we have the fortune to go in front, Morocco, will risk it all at full pelt again.
"We have to show more strength in the moments when the opposition is pressing us."
Japan coach Hajime Moriyasu praised the perseverance of his players after they stunned a second World Cup-winning nation in almost identical circumstances in the space of little more than a week to secure passage to the last 16 .
"Spain are one of the best teams in the world and we knew before the game that this was going to be very difficult, and indeed it was," the enigmatic Moriyasu told reporters.
"But the players persisted and they persevered and they turned the tide of the game. Everybody was excited that we were able to play as one again.
"There were many fans who came all the way from Japan, as well as those that stayed at home. We are gifting this win to the people of Japan, and we are very happy about it."
