The first meeting of the two sides was a fractious affair on Tuesday, especially in the first half as Jeremain Lens was shown a straight red card 10 minutes before the break following an altercation with Colombia's Pablo Armero.
Armero escaped punishment for what appeared to be a stamp on Lens, who reacted by pushing the defender to the ground, for which he was dismissed.
As tempers flared with half-time approaching, both Santiago Arias and Abel Aguilar received cautions for dangerous challenges on Daley Blind and Rafael van der Vaart respectively, the latter having to leave the field with an ankle injury as a result.
After the game, which saw Netherlands extend their unbeaten run to 17 matches, Van Gaal was effusive in the praise of his players.
"I'm very proud, very happy," he said.
"We continued with verve and conviction in the game. We dominated and could hurt them.
"I might have seen our best game, with 10 men we were still the best team and it was 4-0 in terms of opportunities."
On the red card, Van Gaal was critical of Lens, before pointing the finger at Armero for his part in the dismissal.
"He (Lens) should have control," he said.
"That is part of your profession. But I just saw the pictures and you'll see that he gets the heel of his opponent with a speed at which you can reach an injury.
"So I can imagine his reaction, but it should not have happened."
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