#1 Paul Scholes

Who knew good ol' Scholesy was once a striker?! In September 1997, more by luck than by judgement, Sir Alex Ferguson played Paul Scholes in midfield because Roy Keane was out injured.
He was previously playing the role of a strike partner to Eric Cantona or Andy Cole. However, he didn't just prove to be a worthy deputy for Keane, but an even better midfielder than the Irishman!
He grew rapidly as a deep lying playmaker, splitting defences with his pin-point long balls, and breaking nets with thunderous volleys.
They say "necessity is the mother of invention". Perhaps we can look at Scholes as an invention of Sir Alex. We're glad it happened, or else we'd very possibly be deprived of a legend of the game.