And he said: "It is great to see City buying big players and becoming a threat to the top teams. But, in terms of challenging United, they have got a few years to go yet.
"Trophies on the table underline your achievements both in the Premier League and in Europe and United have conquered that for the last 15 years.
"Until City do that I don't think you can compare the two.
"I am saying that with a red hat on. It is great to play against City and it will always be my biggest game wherever I am.
"I'll never forget the derby games at United and it is no different being somewhere else and playing them."