His whole performance in City's 3-1 victory was outstanding. Physically he never seemed to tire, and overall he had the look of a player who is absolutely at the very top of his game.
As well as being supremely skilful and extremely fit, Foden is also a wonderfully intelligent footballer and he showed again against Manchester United that his decision making is one of the things that sets him apart.
By that, I mean when to dribble, and when to pass or shoot - and also, positionally, when to come inside and when to keep his width.