Dutch goalkeeper Cillessen kept in the dark over substitution
Holland will play Argentina in Wednesday’s semi-final in Sao Paulo after Newcastle goalkeeper Krul saved two Costa Rican penalties in a 4-3 shoot-out victory in Salvador.
Van Gaal only made the audacious move to replace Ajax keeper Cillessen – who has never saved a penalty in his senior career – in the dying seconds of extra-time, throwing on Krul after instructing the understudy to perform a length warm-up.
And the Dutch admitted that Cillessen had no idea that he would be taken off if the game went to spot-kicks.
“We said nothing to Jasper because we didn't want him to know before the game,” Van Gaal said. “But as I've explained, every keeper has specific qualities.
“Tim has a longer reach and a better track record with penalties than Cillessen.
“We had discussed it with Tim. He knew about their penalties because he needed to be prepared.
“It worked out. If it hadn't, it would have been my mistake.
“Every player has certain skills and qualities and they don't always coincide. We felt Tim would be the most appropriate keeper to save penalties.
“You have seen that Tim dived to the right corner twice. We are a tiny bit proud this trick has helped us through.”
Van Gaal has confirmed that Cillessen will reclaim his place in goal for the clash against Argentina.
But Krul, who has saved just two of twenty penalties for Newcastle, admitted he was desperate for a chance to impress at the World Cup.
"I did not realise it was so late,” Krul said. “I had spent the whole match on the bench, but we had chance after chance and had not taken them.
“Then you're suddenly thrown in and don't have time to think, but I saved two penalties and now we're semi-finals of the World Cup.
"I knew there was a chance that I would get there and during the extra time it started to itch.