The summer transfer window has hardly been a quiet one, with Manchester City breaking the British transfer record to lure Jack Grealish to the Etihad while local rivals Manchester United have spent a combined £115m on Jadon Sancho and Raphael Varane.
Chelsea have opted to re-sign former striker Romelu Lukaku in a deal that has cost the Blues £97m, while Arsenal made a shock move for Brighton & Hove Albion central defender Ben White, whose £50m fee made him the second most-expensive British defender in history.
However, the biggest move of the window undoubtedly came in Ligue 1, where French giants Paris Saint-Germain secured the signature of six-time Ballon D'or winner Lionel Messi on a two year deal after La Liga wage restrictions prevented him from penning a new deal at former side Barcelona.
Remarkably, Messi's move to the French capital, though expensive in terms of wages, did not cost PSG anything in terms of a transfer fee due to the Argentine being out of contract at Barca at the time of the move.
As predicted by former Arsenal boss Arsene Wenger four years ago, superstars switching clubs on a free transfer is becoming far more commonplace at the top echelon of European football.
This looks set to continue in spectacular fashion next summer, with a whole host of star-studded names eyeing up moves at the end of their deals with their current side.
Ironically, after benefitting from a similar situation in Lionel Messi's case, PSG could now be on the other end of the deal as Kylian Mbappe is reportedly willing to see out the final 12 months of his current contract before upping sticks to Real Madrid this time next year.
The 22-year-old is rumoured to have asked the PSG hierarchy to consider cashing in on him this summer, but after he was quickly rebuffed, the World Cup winner is now biding his time until he can arrive at the Santiago Bernabeu, costing Los Blancos nothing in the process.
It's not all doom and gloom for the Parisian outfit, they could benefit once more from another A-list free transfer in the form of Paul Pogba, who is reportedly keen on returning to his home country after five years of his second stint at Old Trafford.
Pogba's original five-year deal with Man Utd expires in 12 months' time and neither the club nor player seem in any great deal to sign a new one.
The 28-year-old has shown his brilliance in flashes while at United, as recently as last weekend when he became the first United player in Premier League history to register four assists in a single game, but those moments have been all too rare for a man who cost the Red Devils £89m, a then-world record fee.
Both the situations of Mbappe and Pogba ensure Wenger's 2017 sentiments ring true, when he explained: "I think in the future, you will see it more and more. Why? Because the transfers are so high, even for normal players.
"You will see more and more players going into the final year of the contract because no club will want to pay the amount demanded… in the next 10 years, it will become usual."
Few strikers in world football are as highly-sought as Borussia Dortmund's Erling Haaland, who - unlike Mbappe and Pogba - will not be leaving the Bundesliga outfit for free anytime soon.
However, the German giants are potentially spurning a great chance to generate huge cash for the Norwegian international by not parting ways with him this summer.
Should Borussia Dortmund cash in on Haaland this summer? Have your say here.
Though the 21-year-old's contract does not expire until the summer of 2024, it does contain a release clause worth a reported £68m that will come into effect as of the summer of 2022.
This figure is significantly lower than the kind of fees Dortmund could generate for the forward if they were to let him leave the Signal Iduna Park this summer, with interest shown by both Chelsea and Bayern Munich in recent months.
And after a summer transfer window that has shocked the football world, it is very likely that we will see all three of Mbappe, Pogba and Haaland ply their trade for different clubs by the time the 2022/23 season gets underway.
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