Real Madrid coach Zinedine Zidane took full responsibility for the failure as his team were shockingly eliminated from the Copa del Rey by Leganes on Wednesday night, with the manager admitting his job was now on the line in the looming Champions League last 16 tie with Paris Saint Germain.
Leading 1-0 from last week's first leg, Zidane again rotated his side for the return, and a full-strength Leganes team had hit the post through Claudio Beauvue's 20 yard free kick before Javi Eraso evened things up on aggregate by curling a 25 yarder into the top corner near the hour mark.
Madrid equalised quickly after the break through Karim Benzema's classy finish from a tight angle, but the visitors almost immediately went back in front with a key second away goal via captain Gabriel's bullet header at a corner.
Zidane sent on senior pros Luka Modric and Dani Carvajal, and his side pushed Leganes back for the last 20 minutes, but Isco, Benzema, substitute Borja Mayoral and emergency centre-forward Sergio Ramos all missed chances which meant the neighbours could celebrate their first-ever win at the Bernabeu.
Zidane told the postmatch news conference that his team had fallen well below what was expected of them, and the buck stopped with him as coach.
"After the first leg, we cannot play the first half we did here," Zidane said. "In the end the result is logical, as the opponent played their game, and we did not. I am responsible for this, it is a failure for me today. I am very disappointed, and will take responsibility of all this."
Zidane said the main blame for the disaster lay with him, not his players.
"I am angry with myself, not with my players," he said. "My players tried, ran, maybe they played badly, they have part of the blame, but I am the most responsible. You cannot explain our first half tonight.
"That each player might not be at their usual level, that is football, sometimes you are up, sometimes things do not go for you. The players tried, the second half we were better, made chances to score, did not take them.
"The first half I was very disappointed with how we played."
Zidane maintained he did not regret resting his big names including Cristiano Ronaldo and Gareth Bale, and sticking with a Copa lineup of mostly youngsters and reserves, albeit with senior stars Ramos, Benzema and Isco included.
"Some players needed to rest," he said. "When you see the team we picked today, you cannot say it is not a competitive team. That is what I do for each game. On paper this was a competitive team, then in the first half no, we did not compete."
With Madrid also fourth in the La Liga table, 19 points behind runaway leaders Barcelona, Zidane was asked if keeping his job now depended on eliminating PSG in the Champions League.
"Of course," he said. "That is really clear. I am responsible for this, I'm the coach. So I must find solutions. I must take on this situation. I will keep fighting always, keep working, try and look for things to make the team better. Nothing more."
The best calendar year ever for Madrid came under Zidane in 2017 as they claimed five trophies including the Champions League and La Liga double and the manager was asked directly if 2017-18 was shaping up as the worst season in the club's entire history.
"I don't know if it is the worst," Zidane said. "I do not care, really. What I am concerned with is always thinking positively, even after this failure, even tonight when we must apologise to all the fans.
"This is a tough blow for us, but 2018 is not over yet. We must take on the situation, we have a game on Saturday [at Valencia in La Liga], and on February 14 we have a Champions League game."
Not for the first time in recent months, Zidane said the only way for Madrid to turn things around was to just stick together and work harder.
"What we must do is think that hard work is how we get out of this," he said. "We must give more, me first, as all that we have given so far is not enough, we must give more, train harder, help each other more, and we will try and do that.
"You can ask 'what happens now?' We will continue, we must change this, there are many games left to do it. Today is a failure for me."