Robson admits the first time he saw Fergie in full flow he was struggling not to laugh - because he was just glad it wasn't aimed at him!
The former United and England captain said: "I did think it was weird, the first time he attacked Paul McGrath with the hairdryer. You just had to hide your head because you'd start laughing that it wasn't you!
"The boss was giving him a b*****king for seeing him do something in the game he wasn't happy about.
"He's probably the greatest club manager there has ever been. He changed it around at Manchester United.
"He's built five different teams over the years and you could see how hard he worked on the youth system. He did a fantastic job on that side of it and to win that many trophies is unheard of."