Erik ten Hag delivered a scathing assessment after a Manchester United dismantling by Liverpool left him without explanation for an "unprofessional" and ill-disciplined performance.
United were routed 7-0 by their old foes at Anfield as Cody Gakpo, Darwin Nunez and Mohamed Salah – the latter becoming Liverpool's record Premier League scorer – all scored braces.
Roberto Firmino added a late seventh to cap a United humiliation as the Red Devils suffered their joint-heaviest competitive defeat, ending any murmurs of a potential quadruple push after EFL Cup success.
It marked Ten Hag's heaviest loss in what was his 481st match in management, and the United boss gave a brutal appraisal of his lacklustre players on Sunday.
The Dutchman told Sky Sports: "I don't have an explanation. In the first half we were quite in control. At the start of the second half we gave two goals away.
"There was no team anymore. We didn't stick to the plan. There were 11 individuals. I don't know, it's really bad. I have given my opinion [to the players]. It was unprofessional.
"You always have to stick together as a team. We didn't do that. There was no discipline. You have can setbacks, but you have to stick together and do your job."
Liverpool enjoyed their biggest victory over fierce rivals United, surpassing a second-tier 7-1 rout in October 1895, to further their top-four push.
Jurgen Klopp's side are in fifth and trail third-placed United by just seven points, with the Red Devils desperately in need of a response after an abrupt halt to what appeared to be progression under Ten Hag.
Bruno Fernandes was subject to fierce criticism from United greats Roy Keane and Gary Neville on Sky Sports as Ten Hag's visitors seemingly downed tools in the face of adversity.
"We made the wrong decisions, that for me is unprofessional," Ten Hag added. "I'm really disappointed and angry. We let our fans down; as a squad, as a team, you cannot allow this.
"You have to stick together and support each other and fight for one another. You have to defend – we didn't do that and that is really unprofessional.
"We have made a lot of progress, but you see what happens when you don't keep the standards. What I have said in the dressing room is that this is unacceptable."
United host Real Betis in the first leg of their Europa League last-16 tie on Thursday before Southampton visit Old Trafford in the league three days later.
Ten Hag expects a response, saying: "But also it is only one game, we will bounce back. This team is strong enough and we will reset."