The Dutch left-back, 23, has been amazed at the way Fergie dishes out his famed hairdryer treatment - including to some of United's biggest stars.
He said: "I've never met anyone who gets as utterly furious as the manager. Nothing like that has ever been seen in Holland.
"The bizarre thing is that, no matter who he has a go at, they will have respect for him.
"If there's something he does not like he will let fly at you.
"Above all, if you make a mistake near the end of a game or before half-time because you've lost concentration. That's something he absolutely hates."