Van Marwijk: Dutch must beat mental block
"At the last European Championship we beat Italy and France and everyone in Holland was dancing and then we lost (to Russia in the quarter-finals) and went home," Van Marwijk told reporters at a pre-tournament workship for coaches on Tuesday.
"That (inconsistency) we have to improve on, that is a mental block I think. It is so very difficult to explain.
"I have tried over the last year and a half to drill a stronger self belief into the players. But it is a process," added Van Marwijk.
The Dutch have always had the ability to match the best teams in the world on their day, said the coach.
"We don't have as much potential as Germany, Brazil, England or Italy and so therefore for us it is essential our top players are in form," said Van Marwijk.
"When that is the case we can beat any team. Now we have to learn to do that over a consistent period."
The Dutch have never won the World Cup but were runners-up in 1974 and 1978.
Van Marwijk's team have been drawn in Group E in South Africa along with Cameroon, Japan and Denmark.