Kylian Mbappe has been the subject of transfer talk ever since his breakthrough season at Monaco in 2016-17.
His ability and commercial appeal make him one of the most sought-after footballers in the world, but only a select few clubs could realistically afford him.
Paris Saint-Germain face a quandary as they attempt to keep hold of Mbappe and the situation is complicated by the time that is left on their star asset's contract.
When does Mbappe's PSG contract expire?
Mbappe's current contract with PSG expires in the summer of 2022.
The World Cup winner joined the Ligue 1 giants from Monaco in 2017, arriving on loan initially before a permanent transfer took effect in 2018.
He signed a four-year contract with the club at that point, with the €180 million deal between PSG and Monaco (€145m plus €35m in add-ons) making him the most expensive teenage football and the second most expensive signing of all time, behind Neymar.
Does Mbappe want to leave PSG?
According to PSG sporting director Leonardo, Mbappe wants to leave the club and Real Madrid are keen to secure his services.
In an August 2021 interview with RMC and Le Parisien, the Brazilian said: "Kylian Mbappe wants to leave, that seems clear. If Real Madrid are making an offer, that seems clear.
'We cannot, the week before the end of the [transfer] window, change our plans. If he wants to leave, we will not hold him back, but on our terms."
OFFICIAL: Mbappe has told PSG he wants to leave 👋 pic.twitter.com/mj1KHd0Q04
— Goal (@goal) August 25, 2021
As reported by Goal, by that point Mbappe had already rejected six different offers to renew his contract with PSG, making it clear that he was ready to leave the French capital.
Around the same time, PSG president Nasser Al-Khelaifi made the point that the signing of Lionel Messi would go some way towards convincing the France international to stay.
"His future is clear. He said it himself, he wanted us to have a competitive team," Al-Khelaifi said at Messi's first press conference. "Well, we have the most competitive in the world right now. So there is no excuse for him now. He can't do anything else but stay."
However, if subsequent developments are any indication, Mbappe's mind has not yet been changed.
Could Mbappe leave PSG on a free transfer?
Yes. It is possible that Mbappe could leave PSG on a free transfer and such a scenario has indeed been acknowledged by PSG.
"In terms of our position on Real, it seems like a strategy to try to get a no from us, to show that they have tried everything and to wait for a year to get him for free," argued Leonardo.
If PSG and Mbappe cannot agree a new deal, Mbappe would be free to speak to other clubs from January 2022.
While Madrid have tested the resolve of the French club with an offer of €160 million ($188m/£137m), the proposed fee does not match PSG's valuation.
Of course, if Mbappe absolutely cannot be convinced to stay, it seems likely that PSG would eventually decide to accept a bid in order to avoid losing an asset for no return.
Despite his superstar status and the multi-million transfer fee PSG could potentially command, it is not inconceivable for a player such as Mbappe to leave for free.
Indeed, the French club themselves benefitted from one of the most famous free transfers of all time, recruiting Messi for no fee following the expiry of the Argentine's contract with Barcelona.
In the same season, Sergio Ramos arrived at Parc des Princes after his Real Madrid contract ran out, with Gini Wijnaldum leaving Liverpool to join the club in similar circumstances.
Over the years, plenty of superstars have swapped clubs on free transfers, with the 1995 Bosman ruling being a watershed moment in the history of the game.