Goalkeepers have just 0.4 seconds, the time it takes you to blink, to save a penalty kick.
It's certainly not enough time for a goalie to react and respond.
Thanks to the help of statistics and economist Ignacio Palacios-Huerta (who studied more than 11,000 penalty kicks), they can rely on game theory, though..
Game theory is a popular strategy in economics where the outcome of a situation relies more on how well you predict your opponent's actions than how you perform your own.
It came in handy in 2008, during the UEFA Champions League Final, between Manchester United and Chelsea, sort of. The game came down to a penalty shootout which was the perfect opportunity for Chelsea to put Huerta's advice into action.
By watching videos of Cristiano Ronaldo, Huerta worked out that the football star almost certainly would kick the ball to the right if he paused on the run-up. Ronaldo indeed paused and indeed kicked the ball to the right. Following the advice Chelsea's goalie made the save.
Ultimately Manchester United won the game. But, despite the loss, it proved statistics could help even the odds.
Now the goalie can improve the odds if they start to move before the ball is even kicked, but the goalie still must basically guess a side and just go for it.
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