From the end of Mike Ashley's Newcastle tenure to the beginning of Cristiano Ronaldo's second Manchester United spell, it's been a mad year.

Where do we even start? Liverpool goalkeeper Alisson bagged an actual header in stoppage time, Harry Kane stopped scoring goals - and West Ham became quite good.

It's been a bonkers year

But the most shocking moment of 2021 belongs to Lionel Messi.

No, not his sudden Barcelona exit after 17 years at the club. Think bigger.

Cast your minds back to September 28. Paris Saint-Germain are hosting Manchester City in the Champions League.

With the likes of Messi, Kylian Mbappe, Neymar, Kevin De Bruyne and Bernardo Silva in action, it felt like the most star-studded game of the calendar year.

The Argentine stole the show with a trademark goal, his first in a PSG shirt, reminding everyone of simpler times.

This was a stunning moment - but Messi's work wasn't finished

But PSG's 2-0 victory was also a sign of more complicated modern times.

Two mega-rich clubs owned by states with questionable human rights records - and players lying down behind walls.

The most shocking football moment of 2021 occurred right at the end of the match, when the great Messi was laid out along the ground to block a low free-kick, should the wall jump.

But don't take it from us. Just ask Rio Ferdinand, who was left in utter disbelief at the sheer disrespect.

Can you believe this?

The Manchester United legend told BT Sport: "The moment Mauricio Pochettino asked him to do that at the training ground, someone should've gone in there and said, 'No, no, no, no, no, no.'

"This doesn't happen to Leo Messi.

"No, no, no, no. You can't.

"It's disrespectful, I wouldn't have it.

"If I was in that team, I'd have to say, 'Listen, I'll lay down for you.'

"Sorry, I couldn't have him laying down like that. I can't see it.

"He don't get his kit dirty, that's not what Messi does."

There you have it: football's most shocking moment of 2021.

What next? Ronaldo tracking back?