Netherlands coach Louis van Gaal's surprise decision to allow family visits just hours before kickoff is being credited with helping put his players in the mood to demolish world champions Spain in their World Cup opener on Friday.

The decision was to allow the players to see their wives, girlfriends and children on the morning of the match was a significant departure from the usual style of a coach with a reputation as a no-nonsense hard-man.

"Van Gaal does things his own way and to throw open the hotel to the families ensured he took away some of the pressure," wrote columnist Jaap de Groot on Saturday.

It was the first time he had allowed such visits, just hours before the World Cup Group B tie at the Fonte Nova arena which the Dutch won 5-1.

"It was totally unexpected, I think it will have surprised some of the players too," added Toon Gerbrands, who worked with Van Gaal when he won the Dutch title at AZ Alkmaar.

"It's a new dimension in coaching, typical of Louis," he told the Dutch press.

Van Gaal explained his idea as the Dutch basked in the glory of their stunning victory.

"I believe in a total-person principle - the psyche of a player; how he feels is influenced by his environment," he said.

"I gave permission on Thursday for the wives and children to come around on the morning of the match. The players were pleased with that."

But the Dutch coach was not too keen for that decision to be given the credit for Friday's victory.

"I would not say that is the reason why we won," he said with some emphasis.