Per Mertesacker maintains the whole Arsenal team must take collective blame for failing to hold onto a 3-0 lead against Anderlecht which blew chances of early qualification for the Champions League knockout stages.
he Gunners looked to be cruising towards the last 16 after Alex Oxlade-Chamberlain added to first-half goals from Mikel Arteta, a penalty, and Alex Sanchez, who netted another superb goal strike his initial free-kick was blocked.
However, any hopes of perhaps overhauling Group D leaders Borussia Dortmund, the next European visitors to the Emirates Stadium in a fortnight, were extinguished as Arsenal hit the self-destruct button in allowing the Belgians to recover.
Anthony Vanden Borre, once of Portsmouth, started an unlikely fightback when he slotted in - with more than a hint of offside - just a couple of minutes after the match looked done at 3-0, before rolling in a penalty to set-up the grandstand finale as the Gunners were shell-shocked.
Mertesacker was unable to prevent Aleksandar Mitrovic heading in a stoppage-time equaliser at the near post, but the big German centre-half insists defending is not just all about the last line of defence.
"That was a good warning that everyone should raise their game and give maybe 10% when it is needed," said Mertesacker, quoted by the London Evening Standard.
"When we drop sometimes everyone has to be involved to defend. You can't afford for just five or six players to defend, or just the back four. That is what we lacked especially in the final third and in the last 20 minutes.
"We have to defend better as a team. We did not stop them playing and they are good at it.
"As you could see, even in the final third, when you do not put them under pressure, they can deliver good balls through the middle. They can cause trouble and we just left them playing, so in general that was the problem."
Despite all of the disappointment of the end result, Mertesacker sees no reason why Arsenal should not be able to collect the point from their final two Champions League matches to secure qualification.
"This result is a small setback for us but it is a good warning and we will bounce back quickly," said Mertesacker, who could captain the side at Swansea on Sunday following injury to Mikel Arteta.
"We are really good at that, we have shown that a couple of times. We still have a comfortable situation in terms of going through.
"We want to secure second place and we still have a big advantage after four games."
Arteta, who will be assessed after being forced off with a hamstring injury, lambasted the side for "throwing everything away" during a shambolic closing 30 minutes.
The Spaniard expects a response when domestic action resumes with a trip to south Wales.
"That's the best thing in football, we have another game in four or five days against Swansea away, and it needs to be different," he said on Arsenal Player.
Midfielder Oxlade-Chamberlain accepts Arsenal have to take on board their failings from Wednesday night.
He said: "This is a hard lesson that we can't be complacent and we have to go into those games with full focus for the 90 minutes and get the job done.
"We need to pick ourselves up, so it is a lesson learned and so that we make sure we don't make the same mistakes again."