"He is a talented young player," said Olsen. "He is technically good with a good touch on the ball. It was a little early but, like Sven Goran Eriksson with Theo Walcott, I took him to the World Cup. It was exciting for him and fantastic to see what a World Cup is. It was good for his future and good for the team because he is surely a player who will be very, very important in the next 10 years.
"He had a little dip mentally and physically after the World Cup but he has played the last three or four games under Frank de Boer. You will see him against England but maybe not from the start.
"For the moment he is in the right place at Ajax to develop into a top player. It is too early for him to move to the Premier League and play so many games at that level.
"Not everybody can play so many games with the strength the Premier League demands. Maybe in five years you will see him in the Premier League."