This World Cup hasn't disappointed when it comes to penalty shootouts - most of the upsets of the series have happened in those crucial extra minutes after the game.
So much so, ahead of the semi-final games, there's been analysis at London School of Economics over whether this nailing-biting part of football is truly skill or luck.
Here to explain the science of the penalty shootout is creator of the Squeaky Bum Time podcast, and afternoons producer, Emile Donovan.
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