Arsene Wenger admitted his Arsenal team were mentally unable to cope as they were humiliated by Bayern Munich on a nightmare night in Germany.
Wenger's future is once again under huge scrutiny after his team collapsed at the Allianz Arena and it seems increasingly possible that he will walk away from the Emirates this summer after his 20-year reign reached to a new low.
Drawing 1-1 with Bayern at half-time, Arsenal caved in, conceding three goals in nine minutes and another one right at the end of the game.
Former Arsenal defender Martin Keown called the performance 'embarrassing' and now believes Wenger's time at the club is effectively up. Meanwhile, Rio Ferdinand, a Champions League winner with Manchester United, described the Gunners as 'spineless'.
In a post-match press conference cut short after less than three minutes, Wenger said: 'The real problems were after the third goal.
'We lost our organisation and we looked mentally jaded and vulnerable from that moment onwards.
'The last 25 minutes was a nightmare for us. We looked like we had no response.'
Arsenal equalised an early Arjen Robben goal through an Alexis Sanchez penalty and could have taken the lead before half-time.
But reflecting on their subsequent surrender, Keown said: 'I feel for Wenger now and it's embarrassing.
'They've been outclassed and outplayed and Bayern did it at a canter. It's 20 years and seriously Wenger now must be considering his future because that was embarrassing.
'I can't ever say I'd like to see him go, he's almost my football father. But he's an intelligent man and this is his lowest point ever.'
Wenger and his players must now go through the ritual of trying to pull off a second-leg miracle at the Emirates in three weeks but in reality their season now rests on their FA Cup tie at non-League Sutton United on Monday.
Ferdinand said: 'Arsenal got dismantled.
'In the first half they had Bayern on the ropes. At 1-1 they looked like team to go on and do something, to come away with a draw.
'But I didn't see 5-1 coming. Bayern went into overdrive and Arsenal couldn't deal with it.
'They looked spineless, that's the word. No fight or aggression. I didn't see anyone give a rollicking out there.
'There was no fire in bellies and that's disappointing.'
This will be the seventh successive season Wenger has failed to guide his team past the last 16 of the Champions League.
The Frenchman added: 'I do not look for excuses. I give explanations and it's a shock.
'Tonight we did everything wrong. In this kind of game you need to be focused for 90 minutes.
'I felt the third goal was the killer because after that we had no response.'
Bayern Munich manager Carlo Ancelotti came out in support of Wenger afterwards and said: 'This is football. Arsene has a lot of experience and he has the experience to manage this moment and look forward. Its only one game.
'This was a good game for us.
'They caused us some trouble at the end of the first half but we played attractive football with balance in the second half and everything was okay.
'Maybe this was the best performance of our season. But it is not a final and we have to play a second game. We don't want to make a mistake and be careless so we have to prepare for the second game. We want to play the same again and avoid problems.'
With Wenger refusing to say whether he will sign a new contract at Arsenal beyond the one that extends at the end of this season, the debate about his suitability will now rage.
Keown – who played for Wenger for eight years – added: 'I fear for him really in terms of that should he almost be protected from himself?
'I don't want him to be like a boxer who has been in the ring too long and taken too many punches.
'But this is 20 years of work here and you don't want to lose that.
'He's been magnificent for the football club no doubt but this is a massive low point for him and will only bring forward the change that looks ever more likely at the end of this season.
'That decision will be made not now but at the end of the season and I think it will be him that makes the decision.
'I think the realisation that decision needs to be made is even more apparent after tonight's performance and you could see it almost in his eyes that he knows now, probably reluctantly, that he's going to have to hand over the reins to somebody else.
'Arsenal were in the 2006 Champions League final but what has happened since then?
'It's too hollow. The fans want a proper trophy. The intelligent thing is for the manager to find the right moment to leave and that's something I think the club will strongly look at I'm sure.'