Goalkeepers have the toughest job in football. As the last line of defence, they are trusted to win one-on-one battles against strikers, save penalties, and pluck crosses out of the air, while maintaining the highest possible level of concentration for a full 90 minutes.
A gravity-defying save can turn them into an instant hero, but it only takes one mistake or lapse in judgement for their status to change to villain. The very best shot-stoppers have to be able to cope with that pressure and transmit confidence to the rest of their backline.
That is why any outfield player with the courage to don goalkeeper gloves when their team has no other options has to be commended. It doesn't happen often, but sometimes managers do not have a back-up shot-stopper on the bench to step in after their No.1 picks up an injury or a red card.
A number of top players have put themselves forward in those cases and performed admirably in an alien role, while others have looked completely out of their depth - but all of them should be celebrated.
As such, GOAL is here to run down the top 10 outfield players to fill in between the sticks, starting with a former Arsenal and Chelsea favourite...