Schalke manager Felix Magath admitted his side could be relegated this season if they carry on playing like they did on Saturday.
Only three days after beating Olympique Lyon 3-0 to qualify for the knockout stages of the Champions League, the Royal Blues were brought crashing back down to earth with a 5-0 humiliation at the hands of Kaiserslautern.
Magath, who has promised "consequences", says that is not the way to stay in the Bundesliga.
"If we play every game like we did today then that is not going to be good enough for the Bundesliga," he said.
"There were clearly too many players who read too much into our Champions League win.
"Some do not understand that the Bundesliga is our daily bread and that we have got to perform in it.
"Apart from Manuel Neuer, Christoph Metzelder and Jefferson Farfan, I did not have the feeling that any of my players wanted to win the game.
"I am disappointed and annoyed because I simply cannot understand how you can go into such an important game like this."
Several thousand fans who had made the trip from Gelsenkirchen spent much of the second half with their backs turned and the calls for Magath to be fired increased in volume.
All Magath could do was apologise to them and promise it will never happen again.
"We have got to say sorry to all of the fans who travelled here," he said.
"They had a long journey, supported us for 90 minutes and were bitterly disappointed at the end.
"We must never experience a game like this again."
Kaiserslautern coach Marco Kurz would willingly go through Saturday's 90 minutes over and over again, on the other hand.
"I saw an excellent game from my team and we did precisely what we intended to do," he said.
"We will enjoy this moment."