Former Valencia goalkeeper Santiago Canizares has demanded the resignation of head coach Gary Neville.
Without a victory in La Liga so far, Neville suffered his worst result in his time in charge on Wednesday as Barcelona thrashed his side 7-0 in the first leg of the Copa del Rey semi-final.
The former Manchester United captain insisted he will not resign despite admitting that watching his 10-man Valencia get torn apart by the holders was one of his worst experiences in football.
But Canizares, who twice won La Liga and the Copa during a glittering career at Mestalla, says Neville must accept responsibility for a dark day in the club's history.
In a lengthy tirade posted on Twitter, he said: "VCF's defeat today is the worst I've known since I can remember.
"I'm waiting for the resignation of the coach, as well as an apology. I may be ignorant, but I'm surprised he hasn't done it, I thought he was honest.
"If [Valencia director Jesus] Garcia Pitarch believes in Gary as he said on Monday, I'm disappointed.
"If he lied to us, and tomorrow Pitarch suggests the dismissal of the coach and it's not accepted, it's better for him to leave, too."
Canizares accused the Valencia players of surrendering the match to Barca after the sending-off of Shkodran Mustafi, though he praised the Germany international for braving the media in the aftermath.
"Worse than a defeat is the fleeing of the battle. That should give us a clue as to what these players can do if this becomes really difficult," Canizares continued.
"Mustafi showed his face, and I think all Valencianistas appreciate that. Today before the media and always on the pitch.
"I just want what happened this year to help us distinguish the honest from the dishonest. If we do that, we move forward...
"Finally, this is a test of our valencianismo. To demand decisions is responsible, to desert is not. Amunt!"
Valencia travel to Real Betis in La Liga on Sunday.