Van Gaal picked the Barcelona forward for the World Cup despite him not playing for two months because of a hamstring injury, but his selection is not a decision which has been questioned within the Netherlands set-up.
The 28-year-old played the final 28 minutes of their opening 2-0 win against Senegal, with his shot leading to the second goal.
And after that successful outing Van Gaal hopes to be able to stretch his involvement to potentially a full half on Friday against Ecuador, the other Group A side with three points.
"This is a player who is quite extraordinary and so I have set aside my principles because I consider him to be incredibly important for our team and that is why we did what we did," said the Dutch boss.
"I explained it to the players and I do all this for Memphis and the players are all doing it for Memphis and they accepted it.
"He was individual training in Amsterdam but for us he needs to train with the team and it is very important he gets used to that first.
"We have increased intensity and he has played 30 minutes now and isn't grappling too much with the issues so we are proceeding to the next step, which is 45 minutes.
"We are trying to extend that because the injury he had makes it so difficult to decide when he can start."
In his absence Cody Gakpo has stepped up, scoring the crucial first goal against Senegal.
The PSV Eindhoven forward, who is attracting the interest of some of Europe's top clubs, has only played 10 senior international matches but Van Gaal believes he has the potential to become a World Cup star.
"He is a player with a lot of talent and possibilities but he is young and he is still evolving," added Van Gaal.
"He has a lot of room for improvement and is a personality who will do everything it takes.
"Whether he will now become the star of the World Cup I can't promise you that, but it is possible. I know that for sure, he can become a star."
Ecuador's win over hosts Qatar was memorable for Enner Valencia, who scored both goals and was denied a hat-trick by VAR.
The 33-year-old limped off with a knee injury but is determined to play as if he scores again he will equal the all-time record of scoring in six successive World Cup matches currently held by Eusebio, Paolo Rossi and Oleg Salenko.
Manager Gustavo Alfaro said: "The tests showed that he doesn't have an injury but the trauma is very serious.
"I said the other day that not even fire could stop Enner. If it's up to him, he will play.
"Let's give it the benefit of the doubt and hope he responds well in training."