Stale Solbakken said Copenhagen needed to be "perfect" to have any chance of upsetting Manchester United in the Europa League.
The Danish side face United in the quarter-finals in Cologne on Monday looking to cause a huge shock.
As they prepare for the 2020-21 Superliga season, Copenhagen overcame Istanbul Basaksehir in the last 16, recording a 3-0 second-leg win on Wednesday thanks to a couple of goals from Jonas Wind and another from Rasmus Falk.
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But Solbakken said only perfection would be enough for his side against United, who have lost just one of their past 23 games.