It takes only two hours by plane from Copenhagen to Manchester actually. 
But it is true that there is only a 3-day break between these games.
However Manchester City would still stay strong in my opinion. They are used to playing in tight schedules and they have their most important players back from injury as well. I remember their previous challenge against Chelsea away. It was an unforgettable game resulted in a draw like 4-4.
But this time I don't think Chelsea can resist their opponent that much. I expect a decent win by Manchester City.
It seems to me that Premier League teams are best able to adapt to a busy game schedule. A flight, even a short one, can be tiring, but I’m sure the players are used to it, so it’s just as commonplace for them. As for the first match, it’s not often that City concedes so many goals, and even more so Chelsea has almost no chance at the Etihad. City will attack the whole match, and Chelsea will defend, City will score 2-3 goals, but this time they will play much better defensively. But it is true that there is only a 3-day break between these games.However Manchester City would still stay strong in my opinion. They are used to playing in tight schedules and they have their most important players back from injury as well. I remember their previous challenge against Chelsea away. It was an unforgettable game resulted in a draw like 4-4.
But this time I don't think Chelsea can resist their opponent that much. I expect a decent win by Manchester City.