The 62-year-old's reputation as a meticulous tactician was enhanced when he substituted his goalkeeper and Tim Krul went on to make two penalty shoot-out saves to take the Dutch past Costa Rica in a dramatic finish to their goalless draw.
It continued a run of changes that have influenced the outcome of matches in the Dutch team's favour.
Van Gaal brought on 20-year-old Memphis Depay to score the winner against Australia, while Leroy Fer broke the deadlock with his first touch in their last group game against Chile. Then Klaas-Jan Huntelaar made one goal and scored the next after coming on for the last 10 minutes to give the Netherlands a late last-16 win over Mexico.
But neither Costa Rica nor Mexico were expected to provide as much resistance as they did and both games highlighted the deficiencies in Laranja Mecanica (Clockwork Orange) as the Dutch have become known. If they are to beat Argentina in Wednesday's semi-final in Sao Paulo, there are several areas where the Manchester United-bound coach's side need to improve. The absence of injured Nigel de Jong makes the midfield lightweight. Fer has also been injured and Jonathan de Guzman dropped in favour of Georginio Wijnaldum, who lacks an imposing presence.
One option for Van Gaal is to switch Daley Blind to the middle but that means he will lose out on penetration down the left wing.
Saturday's switch of tactics to a three-man attack did not work, by Van Gaal's own admission, because of a poor performance by Depay, who was indecisive on the ball and gave away possession too easily.
Dirk Kuyt's wingback role also limits the team's width, although his work rate is phenomenal, and Robin van Persie was repeatedly caught offside by Costa Rica's disciplined defensive line. It left the Netherlands relying almost solely on Arjen Robben and Wesley Sneijder, who struck the woodwork twice.
But with Argentina displaying strong defensive qualities and a battling midfield in their last-eight win over Belgium, the Dutch need to find more options and a better balance if they are to reach a second successive World Cup final.
Costa Rica, meanwhile, leave the World Cup unbeaten in open play with a first quarter-final appearance, the scalps of two former champions and some tidy football that mocked their underdog status.
"Costa Rica's heart broken, but soul intact," read one of yesterday's headlines in the Central American nation of fewer than five million people, whose team began the tournament as 4000-1 outsiders. Many eyes had been on Spain and their slick-passing brand of 'tiki-taka' football before the tournament, but within days it was the 'Ticos' who caught attention with deserved victories over Uruguay and Italy.
'Tico-taka', as some dubbed their style of stalwart defending and counter-attacks, carried them comfortably through a 0-0 draw with another former World Cup winner, England, to top a group in which they had been expected to struggle.
Losing some attacking verve, Costa Rica beat Greece on penalties in the last 16 before their quarter-final shoot-out with the Netherlands.
Costa Rica had conceded two goals in the tournament, and that without their best defender, left-back Bryan Oviedo, who had failed to recover sufficiently from a broken leg.
"Unbeaten!" tweeted President Luis Guillermo Solis of the team nicknamed 'La Sele' as well as 'Los Ticos' at home. "A whole nation proud of 'La Sele', and the whole world recognises this achievement."
Costa Rica's consistently good performances had no luck about them and were all the more remarkable given their relative lack of big names. Of the few who do have wider recognition in the footballing world, captain and attacking midfielder Bryan Ruiz, on loan to PSV Eindhoven from Fulham, and striker Joel Campbell, on loan to Olympiakos from Arsenal, have seen their profile rise. Most prominent, though, was Keylor Navas, the 27-year-old goalkeeper who plays for Levante in La Liga. Now being linked with Real Madrid, his reputation was enhanced considerably in Brazil.
"It's an empty feeling," Navas said in the aftermath of Saturday's match, declining to speculate on his club future until he had absorbed the moment with the national time. "But this team can leave with their heads high. We didn't lose a single game. It's hard but that is life."
Costa Rica supporters are hoping their Colombian coach, Jorge Luis Pinto, stays on. "We are not a big power but we demonstrated things," he said, singling out his "brilliant, spectacular" goalkeeper.
Even though they were defeated, Costa Ricans danced, waved flags, beat drums and beeped horns on Saturday night in the capital San Jose. "Honestly, this loss is a win for us because we got so far," said a flag-draped Alexander Acevedo, 25.