Manchester United legend Denis Law believes Manchester City will be a big threat to the Red Devils' city dominance.
Law, who also played for City, said: "Apart from being up there near the top, City are playing good football. It's great to see them up there.
"At United it's great to see such exciting players. These three (Ronaldo, Rooney and Tevez) have the potential to emulate our achievements in the 1960s."