"We are a better team than last year, no doubt about it but I think City is also a better team than last season," Mourinho said.
When asked how good City are, Mourinho replied: "Very good."
Mourinho acknowledged the derby represents a big opportunity for his United side but was keen to stress the game is still only worth three points.
"To me it is one more big match against one of the best teams in the country, the first against the second. It is a big match," Mourinho said, when asked about the magnitude of the game.
"I don't need to know that a derby is something special for the people. For us, in the end, it is three points but honestly, I think for the people born in the city and feeling the colours, it is a good positive rivalry and a special match."