Arsene Wenger was left berating an "extremely poor" defensive display as Bayern Munich thrashed his Arsenal side to leave their Champions League hopes dangling by a thread.
Having beaten Bayern at the Emirates Stadium a fortnight ago, the Gunners brought a decent record to Germany only to be blown away by one of Europe's super-powers.
Robert Lewandowski needed 10 minutes to head the hosts in front before a brace for Thomas Muller and goals from David Alaba and substitute Arjen Robben wrapped up a convincing 5-1 win for Bayern.
Arsenal had a potential Mesut Ozil equaliser correctly ruled out for offside as Olivier Giroud pulled one back for the Premier League side but by that time they were four goals behind having been torn apart by a rampant Munich frontline.
The result means Arsenal have lost three of their four Group F fixtures and sit bottom of the group - with wins in their remaining two matches not enough to guarantee progression.
Wenger's cause was not helped here as both Hector Bellerin and Laurent Koscielny were ruled out with injuries - and the two players drafted into the Gunners defence were culpable.
Gabriel partnered Per Mertesacker at the heart of the defence but played Lewandowski onside for the opener while Mathieu Debuchy completely missed a Philipp Lahm cross that led to Muller doubling the lead.
And Wenger was in no mood to sugar-coat his side's deficiencies at the back as he saw Arsenal suffer their heaviest Champions League defeat in their history.
"I believe first you have to give credit to Bayern for their quality and on top of that we made things quite easy for them with our defensive performance," he said.
"We were extremely poor defensively and were not at the races. The funny thing was that when we went forward every time we looked like we could create chances but with a defensive performance like that you are going nowhere."
Wenger stopped short of labelling the performance the worst defensive display of his lengthening tenure and admits progression into the knockout rounds is looking unlikely.
"My memory is not good enough to tell you in 19 years if it is not the worst performance," he said.
"It will certainly not remain in my memory for anything positive.
"There is still a chance to qualify, Olympiacos have to lose here, we have to beat Zagreb and then beat Olympiacos in Olympiacos, there is a small chance but it is a real one.
"We have to realise with the kind of performance we have today that our chance is at a minimum."