It's a fight against the two then although the only reason why I feel Manchester united would be having an upper hand in the race would be because of the influence of the present coach as he was the former coach of the striker and would have more leverage in convincing him to come play and help united in their quest to refurbish the old glory of the Manchester united we know.
At the moment Manchester United should have more luck when meeting Manchester City who in their last ten games have only managed to win one match when hosting Nottingham Forest. So Manchester United can take more steps to make more surprises through their new manager's breakthroughs this weekend when they play as guests at Manchester City's home later. Because Manchester City are in a less than good condition so the level of luck for the match should be more potential for Manchester United to get this weekend.
Manchester United and Manchester City are both in a slump right now so I don't think there is one that has the advantage in this weekend's Manchester derby, in fact I see the overall strength of both teams and I think Manchester City is still stronger than Manchester United especially since the match will be played at the Etihad Stadium which will certainly make it much more difficult for Manchester United with their new coach.
With the poor performance of City yesterday, I don't think that they have a better chance of Winning United in the upcoming Manchester derby because, City does not have the quality you think they have anymore, and United might shock you on that day by winning City. I see the game as 50-50 in favour of none of them.