The first person Holland coach Louis van Gaal turned to after his side had beaten Costa Rica after a dramatic World Cup quarter-final on Saturday night was Frans Hoek, his goalkeeping coach.
Aside from a spell as Poland goalkeeping coach under Leo Beenhakker (2005-2009), Hoek has worked with Van Gaal at Ajax, Barcelona and Bayern Munich, and the recognition from the Dutch coach was significant.
Hoek's philosophy goes some way to explaining why he made the decision. He divides his goalkeepers into two categories: A-type and R-type.
A is for Anticipation, and refers to ball-playing goalkeepers who are happy to participate in possession, not scared of a back pass, and quick to move if his defence plays a high line.
"Anticipation goalkeepers could be easily used as field players, as they are able to function as the eleventh player," Hoek explained.
Edwin van der Sar and Fabien Barthez were both A-type players.
R is for Reaction. "This type of goalkeeper is an absolute winner. He will go to any extreme in order to win, is physically strong and has a high muscle tone. He is very strong and has quick reactions; a lot of muscle strength and great charisma," Hoek told Soccer Coaching International magazine.
The R-type is a great shot-stopper but less good at one-on-ones. Dino Zoff, Oliver Kahn and Gordon Banks were R-types.
So which type would Hoek prefer to have in goal for a penalty shoot-out?
It's apparent from the events from Salvador that it's the R-Type.
As soon as Krul came on the pitch, he showed the physique and charisma of an R-Type, prowling his area and distracting his opponents by telling them he knew where they would kick the ball.
As it turned out, he did know: he dived the right way for five kicks out of five automatically increasing his chances of saving a penalty by 30% - and saved two of them, both to his natural side, his left.
In the course of researching my book Twelve Yards: The Art and Psychology of the Perfect Penalty, I looked into the role coaches play in the shoot-out and only discovered one example of this goalkeeper-substitution tactic working in the past.
The coach was Felix Emordi, the club was Nigerian side Enyimba and twice in the 2004 African Champions League in the semi-finals and final he subbed off first-choice goalkeeper Vincent Enyeama (yes, the very same) and brought on Dele Aiyenugba for the penalty shoot-out.
It worked against Esperance in the semi-final and in the final against another Tunisian side, Etoile de Sahel, when, Aiyenugba saved Sabeur Ben Frej¹s kick and Enyimba won the shoot-out 5-3.
Other efforts to make this work have not been quite so successful: in 1996, Leicester City coach Martin O'Neill took off goalkeeper Kevin Poole and brought on Zeljko Kalac, a penalty specialist, after 119 minutes of the first division promotion play-off against Crystal Palace.
Before full-time, Steve Claridge scored a winner for Leicester and Kalac did not touch the ball.
The opposite happened to Greuther Furth coach Mike Buskens, who swapped Max Grun for Jasmin Fezjic two minutes before the end of the 2012 German Cup semi-final against Borussia Dortmund.
Two minutes was long enough for Dortmund to get a winner, Ilkay Gundogan shooting from the edge of the area on 119.56 with a shot that hit the post, struck Fezjic on the shoulder and cannoned into the net.
The idea that coaches play a crucial role in the dynamics of the shoot-out was confirmed to me by Sir Dave Brailsford, former head of British Cycling, who said that coaches must take responsibility for what happens in the shoot-out to the extent that in the case of non-regular penalty-takers, he would even tell them where to aim their penalties "to give them one less thing to worry about."
So where does this leave Holland ahead of their semi-final against Argentina? Actually, in rather good shape.
The likelihood of scoring in a shoot-out after winning your previous one increases from 76% to 83% - and if you have won your last two shoot-outs, it increases to 89%.
Germany's penalty record is second to none: five wins out of five since a Panenka-inspired defeat in the Euro 1976 final and a 93% conversion rate.
Brazil, though, have hosts' momentum on their side (Italy in 1990 were the last hosts to lose a shoot-out; since then, France, South Korea, Germany and Brazil have won them) and the best goalkeepers' saving ratio, 32%, of any of the major nations.
Next, though, Van Gaal has the small matter of trying to stop Lionel Messi and Argentina.
Already in this tournament, he has shaken off two traumas for the Dutch psyche avenging the 2010 World Cup final by smashing Spain and then the penalty shoot-out success so the small matter of getting past Holland's 1978 final conquerors should be a walk in the park.
Ben Lyttleton | Follow on Twitter
Ben is the author of Twelve Yards: The Art and Psychology of the Perfect Penalty, out now - you can buy it from here
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