The 2018 FA Cup final between Chelsea and Manchester United hinged on a key refereeing decision.

With barely 20 minutes on the clock at Wembley Stadium, the Blues won a penalty courtesy of Phil Jones' clumsy tackle on Eden Hazard.

The result was an emphatic one with Hazard duly stepping up to take the spot-kick himself and calmly rolling the ball past David de Gea for the only goal of the game.

What happened in the 2018 FA Cup final?

Not only did it ensure that Antonio Conte finished his Chelsea reign with an extra piece of silverware, but it also meant that Jose Mourinho's infamous second-placed season ended on something of a damp squib.

Besides, try as the Red Devils might, they simply couldn't bounce back from what was undoubtedly a shrewd refereeing decision by Michael Oliver.

Hazard celebrates with the FA Cup.

Soccer Football - FA Cup Final - Chelsea vs Manchester United - Wembley Stadium, London, Britain - May 19, 2018 Chelsea's Eden Hazard celebrates winning the final with the trophy Action Images via Reuters/Andrew Couldridge

It's not easy being a match official at the best of times, but it's especially pressurising when you're holding the whistle in the final of football's oldest cup competition.

If anything, though, that only makes it even more engrossing and fascinating to listen to Oliver's decision-making process as Chelsea's game-deciding penalty unfolded before his eyes.

And we only know about that as a result of rare access to the referee's microphone on the day, which is something that many football fans believe should happen at every single game.

What does a referee say during football matches?

In a remarkably rare occurrence, NBCSN were provided with the audio of Oliver's conversation with his assistant referee as the game's pivotal moment took place under the Wembley arch, as corroborated by the Daily Mail.

It was given to them by Professional Game Match Officials Limited (PGMOL) and duly serves as one of the most eye-opening looks behind the curtain at the world of elite refereeing.

Hence why, more than four years later, we continue to be absolutely fascinated by it.

So be sure to get a taste for what a world of mic'd-up refereeing might actually sound like by listening to one of England's best referees making a huge decision in the FA Cup final.

Video: Audio from Michael Oliver's mic in the 2018 FA Cup final

So interesting, right?

The fact that you can hear everything from the panting of Oliver to the protests of the United players really puts you in the shoes of the referee, highlighting just how chaotic and fast-moving the world of football officiating truly is.

To not only have to speak yourself, but to be communicating with your assistant, the VAR and the players around you at the same time, all while keeping your composure and thinking things through, must be so, so difficult.

And with referees set to announce the reasons for VAR decisions via a microphone at the upcoming FIFA Club World Cup, it's perhaps a taste of what fans can expect going forward.

You can't help feeling for the referees duly having to go through yet another stage of communication, but there's no denying that it will absolutely fascinating to learn more about how the big decisions are being made. Bring it on.

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