Per Mertesacker is confident that Arsenal will "bounce back quickly" from Wednesday's 3-3 draw against Anderlecht.
Arsene Wenger's side looked to have secured their place in the last 16 of the Champions League before conceding three goals in a dramatic last half-hour at Emirates Stadium.
While Mertesacker was disappointed to let that lead slip, the German defender is expecting a positive response at Swansea City on Sunday.
"In the next couple of days, we will have good training sessions together and I think the spirit will come back"
"I think it will be a tough game anyway," he said. "That will be totally different. You cannot compare any game to another.
"We will bounce back quickly, we are really good at that. We have shown that a couple of times. That was a good warning [on Wednesday] that everyone should raise their game and give maybe 10 per cent more when it's really needed.
"In the next couple of days, we will have good training sessions together and I think the spirit will come back, because we have a good team and our potential in our game will come back very quickly."
Mertesacker says the Arsenal squad must take collective responsibility in order to improve defensively.
"We have to defend better as a team," he said. "Even when we dropped [back, Anderlecht] always looked dangerous.
"We need to be more aware of that, to defend better as a team. When we drop sometimes everyone has to be involved to defend. You can not afford for just five or six players to defend, or just the back four.
"That's what we lacked especially in the final third and in the last 20 minutes."
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