Arsenal boss Arsene Wenger has said his team were "mentally unready" after they lost 3-1 to Monaco at the Emirates Stadium on 25 February, adding that they were "suicidal defensively".
Speaking at the post-match press conference, Wenger made no excuses for his players' limp display after the full-time whistle, calling it "a horrible night".
"Mentally we were not sharp enough to get into this game and we paid for it," he told the news conference.
"The team is strong physically but we missed the chances. If you look at the number of chances we missed tonight you can't do that at this level. Defensively we were not at our level but our weakness was more mentally.
"Even at 2-1 how can we with one minute to go just leave the whole half open? It is difficult to understand.
"We controlled the game quite well, but with their first shot they scored a deflected goal. Everything went for them tonight, but on top of that you see as well why Monaco have done well in the group stage. They are well organised and physically very strong, they did not weaken through the game, but we did."