Manchester United legend Sir Alex Ferguson has discussed this week's 'four world class players' controversy.

The 73-year-old, who was in the Old Trafford hot seat for 27 years, made the suggestion in his new book 'Leading'.

The book stated only Eric Cantona, Ryan Giggs, Paul Scholes and Cristiano Ronaldo could be defined as world class.

"We'll that's the area in which the press have not given it the proper publication, the proper reason for saying this," Ferguson told SiriusXM FC.

“If you look at the time I was at for United for 27 years, I had some fantastic players, some great players. I never said those players were not great, they were fantastic.

“But in the context in my opinion, it was a qualified opinion, that some players make a difference, and that's what I judged.

“Eric Cantona, when he came into the club in 1993 he made a difference. Paul Scholes and Ryan Giggs played for 20 years in the Premier League, that made a difference to us.

"And of course, Cristiano Ronaldo's performances, he is a world-class player as everyone knows. Him and [Lionel] Messi the two world-class players."