“That is not normal,” Tim Krul said after coming on as a 120th-minute, penalty shootout specialist in Holland’s quarter-final win over Costa Rica. “You sit the whole match on the bench and then you have to go in and save the penalties. I don’t know what I can say.”

It is indeed not normal, and most of the attention will of course be on Louis van Gaal’s remarkable decision to replace Jasper Cillessen, who had played well in normal and extra-time, for a goalkeeper going into a shootout cold and without a minute of competitive football in almost two months.

Van Gaal looked like a genius because it worked, but of course things would have been rather different had Krul fumbled and cost the Dutch a place in the World Cup semi-final. Indeed, Krul’s penalty-saving record is not actually that great, keeping out just two of the 20 he has faced since joining Newcastle five years ago, but perhaps Van Gaal’s decision was rooted in something other than simple statistics.

“I psyched them out,” Krul said after the game. “You try to do everything you can without being too aggressive. I tried to get in their minds. I watched them [Costa Rica] against Greece and studied them and I told the players that I knew where they were going to shoot to make them a bit nervous. Maybe it worked.

“It happened before when I played against Frank Lampard: I told him that I knew and I saved it. I just tried that again. I’m so happy it worked today.”

Did Krul go a little over the top? Did he go too far in his intimidation of the Costa Rican players? This was, after all, not merely the wobbly legs of Bruce Grobbelaar or Jerzy Dudek but fairly naked aggression in the faces of the opposition – there is a fine line between gamesmanship and plain cheating, and Krul undoubtedly flirted with that line.

Krul approached each penalty taker and not only stared them down, but preyed on their nerves by yelling at each man that he knew which way they were going to go. Even after one of the penalties that went in, Krul continued to hammer the message home and made everyone aware that he had not been out-thought, letting the scorer Giancarlo González know in no uncertain terms that he still knew.

Oddly, that was the occasion on which Krul most obviously skirted the boundaries of acceptable behaviour, acting after the goal as if González were the unsporting one by doing something as impertinent as scoring. Krul guessed right on each occasion, with even the penalties that went in whistling past the Newcastle goalkeeper’s fingertips, and this was not because Krul took the Peter Shilton approach of waiting until the kick was taken before moving.

On all five occasions Krul moved in the correct direction before the ball was struck, and whether that was down to guesswork, brilliant preparation or old fashioned mind-games is quite possibly moot, but it is highly unlikely that his actions did not at least have an effect.

What Krul basically did was to take advantage of the disparity in nerves present in every penalty shootout. As the old cliché goes, there is comparatively little pressure on the goalkeeper because they are not expected to save penalties, but the takers are very much expected to score them, even though in this scenario there was more pressure than usual on Krul, because of his status as a “specialist” penalty saver.

The almost crippling nerves were plain to see on the faces of every taker, even Robin van Persie, who is about as cold-blooded a striker as you could hope for, and in moments like that it does not take much for self-doubt to creep and spread. That is often all that is required for an error to occur, when the time-honoured advice of “pick a spot, don’t change your mind” starts to falter.

Each player probably did know exactly where he wanted to put his kick, but after a 6ft 4in goalkeeper bears down on you shouting that he knows exactly what you are about to do, it creates doubt. Does he really know? Is this a bluff? Has he been studying? Is my body language too obvious? Am I telegraphing the kick? Is the best course of action to stick with the original plan or to change my mind?

If those questions appear in the mind of a penalty taker in the moments before striking the ball, even if they don’t change their mind, then it is enough to create a moment of indecision that could prove crucial. Indeed, the two that Krul saved, from Bryan Ruiz and Michael Umaña, were not those of particular conviction, with neither right in the corner of the goal and Umaña’s at the archetypal “nice height” for Krul to paw away to make him look like Lev Yashin and Van Gaal a genius.

This was undoubtedly gamesmanship, but it is worth noting that Keylor Navas, the otherwise excellent Costa Rica goalkeeper, tried exactly the same thing, approaching each Dutch taker before their kick and attempting to intimidate them. Navas was perhaps a little less aggressive than Krul but the theory was still the same, the difference being that the Dutchman converted that into practice more effectively than his opposite number.

Indeed, if Krul had been unsuccessful and Costa Rica had gone through, would his apparent aggression even be a talking point?

Almost certainly not. Penalties are a psychological affair – if they weren’t, then how to explain the number of brilliant players who have made a total mess of things down the years? Roberto Baggio, Franco Baresi, Michel Platini, Ronald de Boer, Roberto Donadoni, Andriy Shevchenko, Steven Gerrard, David Trezeguet – briliant technical players, but all of them have missed in World Cup penalty shootouts.

On this occasion the whole thing was a psychological trick, started by Van Gaal in bringing on Krul in the first place, making him seem like an intimidating penalty-saving king even if he wasn’t one, and continued by the goalkeeper by playing with the minds of his opponents.

Krul undoubtedly pushed the boundaries of sportsmanship and fair play but he did not break them, rather merely harnessing the nerves of the situation for his own means, and creating fine theatre at the same time.

More on goalkeeping at the World Cup

The top 10 goalkeepers in Brazil

Manuel Neuer’s immense presence powers Germany’s World Cup success

Mexico goalkeeper Guillermo Ochoa: the World Cup's new internet darling