"Did we see then that he would be the most expensive defender in the world? If I said yes, I would be lying," he admitted to Goal. "It went step by step.
"At first, we thought 'OK this is a talented player'. After a few weeks, it was 'alright, he has his place in the starting line-up', and then after six months it was 'he has nothing to do with us in Groningen'. So, it was progressive.
"When I arrived, he was very young. He was not yet a regular part of the first team. But from the first weeks, you could see he was a player apart.
"A great defender, of course, but he was also very good and comfortable with the ball at his feet.
"It was obvious that he was a real talent, and he quickly gained his place in the starting line-up. And it did not take too long to see that he was a really great player."