It's a strange rule that goalkeepers have to take penalties.
It would be more fun if the first 5 have to do the penalty shootout. The goalkeeper knows where they scored the last time and it would be a more psychological game. Will they dare to shoot in the same corner or will they switch?
That was what would happen if De Gea scored. They are again the first 5 players to score the penalties.
The rules are even simple, if you are tied after the 5 penalties, the penalties remain the rest of the players who were in play to score. If at the end of the 11 players, everything is still tied, repeat the sequence again.
What is the probability of reaching the goalkeeper? It is not common. Usually after 6 or 7 penalties, someone fails.
But in this game it happened. All the players were making the penalties well.