Grant Brebner conceded Melbourne Victory had hit rock bottom by conceding five second-half goals in the most humiliating loss in the former A-League power club's history.
Victory were torn apart at Marvel Stadium on Saturday night as rampant Melbourne City put the hosts to the sword in a record-breaking 6-0 derby demolition.
And while City's performance was breathtaking, propelling them into the top six with a third consecutive win, the fallout will centre on last-placed Victory and their under-fire coach.
"It quite simply wasn't good enough," Brebner said.
"I'm not going to sit here and try to find excuses for it.
"It was an unacceptable 90 minutes, never mind the second half, it was humiliating.
"I didn't think before the game a result like that would occur and it's something that we need to continue looking at because it's not a position that anybody at this football club wants to be in - most importantly our members and fans."
Victory have just two wins and a draw from 10 matches this season under Brebner, who could not guarantee he will still be in charge of the club next week.
"I don't really want to think that far ahead just now," he said.
City dominated the clubs' 33rd meeting from the outset and took a first-half lead in fortuitous circumstances when the ball deflected off the inside of Jamie Maclaren's left leg and dribbled over the line.
But it was well deserved and goals to Florin Berenguer and Rostyn Griffiths within 11 minutes of the restart were a fair return on the run of play.
McLaren twice teed up Connor Metcalfe for goals in the space of three minutes to rub salt in Victory's wounds and substitute Stefan Colakovski completed the rout when he fired a low shot past helpless goalkeeper Max Crocombe in added time.
The six-goal margin was the greatest in the Melbourne rivalry's history, eclipsing City's 4-0 win almost seven years ago to the day, when they were still known as Melbourne Heart.
And it came despite golden boot leader Maclaren blasting a penalty kick against the crossbar in a string of missed first-half chances.
A month ago, City were struggling after three straight defeats, but they have engineered a stunning turnaround to re-emerge as title contenders after finishing runners-up to Sydney FC last season.
"I know you guys are saying it's a big thing because it's a derby, but it was another game for us," City coach Patrick Kisnorbo said.
"The important thing is our performance and how we executed that.
"That's what I'm happy about the most."
Australian Associated Press
