Arsenal manager Arsene Wenger accused his players of "suicidal" defending as he offered up few excuses following a surprise 3-1 home defeat to Monaco in the Champions League.
The Gunners looked to have given themselves a lifeline late on, with Alex Oxlade-Chamberlain scoring in the 91st minute following goals from Geoffrey Kondogbia and Dimitar Berbatov for the Ligue 1 visitors.
But Wenger admitted his team's hopes of making it through to the quarterfinals of the competition were hanging by a thread after Yannick Ferreira Carrasco fired an injury time goal for Monaco that restored their two-goal advantage heading into the second leg.
The last-16 pairing with Monaco appeared to offer Wenger and Arsenal a glorious opportunity to progress through to the last eight of Europe's elite competition, but the chance appears to have slipped through their grasp.
"It was a horrible night, but congratulations to Monaco," Wenger told Sky Sports. "They fought well and caught us on the break, but we had both aspects wrong. We had the chances we didn't take and we were suicidal defensively.
"We were opened up on the second and third goal. We knew at half-time that it was important that we kept our nerve and with the vast experience we had through this competition, we knew we couldn't afford to do this.
"On that front, we are very guilty, even at 2-1. How can we just leave it open the whole half? It's difficult to understand. We knew before the game what they would do. Absorb pressure and hit you on the break. What happened? Exactly that.
"Everything went for them tonight, but on top of that you can see why Monaco has done well in the group stage. They are well organised and physically very strong. They didn't weaken through the game, but we did."
A downbeat Wenger went on to suggest his side still have hopes to make it through to the quarterfinals, even though he accepted their hopes are now fragile at best.
"The task is massive now," he added. "The third goal makes it even more difficult. We will have a go, of course, and see what we can do there.
"It's very, very disappointing, but the Champions League is down to performance on the day. When you don't perform to the level that is requested for 90 minutes, you are punished because the teams have the quality."