Per Mertesacker says Arsenal must keep their standards high for the whole of Saturday's game - or risk losing to Manchester United.
Arsene Wenger's team were pegged back after taking the lead in each of their two fixtures before the international break, against Anderlecht and Swansea City.
Mertesacker is determined to return to winning ways at the weekend and says the squad have used the last fortnight to regroup.
"We had a consistent 60 minutes twice and we have to extend that to convert it into a decent performance for 90 minutes," he told the official matchday programme. "We lacked something after 60 minutes, just small mistakes, and that turned it completely around.
"We thought that we were secure and safe after 60 minutes and we lost our head twice. That’s really unusual because when there was a small setback last season we came back even stronger.
"The international break may help us, as everyone has [had] a chance to think about their own international stuff before coming back and regrouping even stronger. Normally you have to finish strongly before the break, but we [had] to use the break to regroup and think about slight adjustments in terms of protecting the lead when we have it.
"We also need to cover and protect our own half even more, and think about how quickly we switch on when we lose the ball - those are things that will be interesting for us to think about in the next two weeks.
"At the moment we are really spot on for 60 minutes and we cannot afford to lose our heads again, we have to be consistent over 90 minutes and we need to get that in our mind."
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