Yeah Manchester United will find it very difficult to beat Manchester City because there performance last season and this season is very poor, even there goalkeeper are not helping the club.
Besides there is no way we can compare Manchester City performance and Manchester United because there is a big difference so Manchester United doesn't stand a chance against Manchester City so actually is a winning game for them.
This season the Manchester Derby is very unbalanced because the strength of the Manchester United team is still inferior to Manchester City so the match will not be fierce enough even though it can also be interesting to see because there are still quite a lot of Manchester derby fans this season. Everyone can see from the results they have got this season after nine matches and it is very clear that Manchester City still has very good quality players so that Manchester City's performance is still much more mature this season even though one of Manchester City's mainstay players is still injured.
Seems you are forgetting the some key Manchester City players are facing injuries. This has shown in their recent performance even though they got the results, it was obvious they have dropped in form. With Man United recent win over Sheffield United, their morale will be so high that they can put of a serious fight against City. It will really be an interesting derby