Manchester City did not look strong. Manchester City are strong no doubt, but I think Manchester City are doing much better in the Premier League than the Champions League because I can see that they concur with many clubs there than here. Although I don't focus on the Champions League like Premier, Real Madrid are strong too. But seriously, I can’t predict between Manchester City and Real Madrid. Although Real Madrid has shown some signs that they are ready for the title this season, to me, Inter Milan have been dominant throughout the season, so let's wait and see how the remaining matches will go. Maybe Inter Milan will remain dominant and no team will concur with them, so let's see how they will do.
In fact Manchester City could have destroyed Copenhagen in the first leg by a much bigger goal difference.
Copenhagen must be really thankful for Grabara's great goalkeeping skills. His making many saves helped them not lose the game by an embarrassing score. However I don't know if even Grabara can save Copenhagen in the second leg. 
I liked Manchester City a lot in the Luton game they played a short time ago. Especially Haaland and De Bruyne were just marvelous!
As long as this duo is very productive I would always expect huge performances from Manchester City in every competition.