He said: "I see a bit of myself in Hiddink because, like me, he hides his passion and tries to control it.
"We're both a long time in the job and we don't make too much noise.
"There are certain times when you have to get angry. We all have a dark side and you can get upset by small things every day.
"But you have to learn to control that anger. Because when you are angry you are not in control. And then you achieve nothing."