City is the favorite to win, no doubt about it but it does not mean that United has no chance to win. A small chance is still a chance and may make a big surprise in the final result. United can be more motivated in this match to keep the chance for the last spot of CL next season. It will be hard match for United obviously but we all know that anything may happen in soccer. I will be risking few dollar to bet United with odds 10x not because I'm sure that United will win but I like to take a risk and bet on the underdog.
Manchester City are stronger and are a favorite team to win but Manchester United have good players. They are not as strong as Manchester City, lack of stability but in a single match, they already shown that they can beat big clubs in Premier League. With Manchester United and their instability, it's hard to predict their performance in big matches. Sometimes they do good, win in surprise of all but other times they play very poorly and got big defeats surprisingly too.
Latest forms of two teams are opposite and Manchester City are performing better and they probably will get three points from Manchester United in Manchester derby.