Per Mertesacker believes all Arsenal's players must raise their game by "10 percent" in the wake of the collapse against Anderlecht in the Champions League on Tuesday night.
The Gunners were strolling to a place in the last-16, three goals up against the Belgian champions with under half an hour remaining.
But they capitulated with Anthony Vanden Borre scoring twice, once from the penalty spot, before Aleksandar Mitrovic's 90th-minute header completed the superb comeback.
It means Arsenal still need another point from games against Borussia Dortmund and Galatasaray to ensure their progress, and Mertesacker hopes it will act as a wake-up call for the whole squad.
"That was a good warning last night that everyone should raise their game and give maybe 10 percent more when it is needed," the German was quoted as saying in the 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 [Anderlecht] 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.
"Last night is a small setback for us but it is a good warning and we will bounce back quickly. 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."
Captain Mikel Arteta, who had scored the first goal of the night with a spot-kick, could not hide his disappointment at the capitulation, which means they will almost certainly have to settle for second place in the group behind Dortmund and a tough last-16 tie.
"It is just not good enough," Arteta said. "We have thrown everything away. Even after conceding the first goal we still had a two-goal lead.
"It has blown our chances of winning the group and that is the main aim at the start of the competition. We need to analyse the mistakes and what happened in the second half, because it is not at the level required at this club.
"We have another two chances still, but you can't miss your chances in the Champions League, because every team has qualities and you can see what happened."