Real Madrid have not given up hope of landing Kylian Mbappe this summer, according to reports.
Messi is the fourth player to have arrived at the Parc des Princes on a free transfer this summer, after Sergio Ramos, Gini Wijnaldum and Gigio Donnarumma.
The Argentina international looks set to form a star-studded attack alongside Neymar and Mbappe.
PSG hope that the arrival of Messi will help to convince the Frenchman to commit his future to the club.
Mbappe is out of contract next summer and has yet to agree fresh terms with PSG, provoking speculation that he is looking for a way out.
Real Madrid are thought to be at the front of the queue to sign him, and one report suggests they may yet try to do so before the transfer window closes at the end of this month.
Cadena SER writes that the Spanish giants are weighing up a £102m bid for the 22-year-old.
Mbappe's representatives expect the youngster to make a decision on his future on Monday.
The former Monaco forward was booed by a section of PSG supporters during Saturday's 4-2 victory over Strasbourg.
Mbappe scored the second goal as PSG registered their second win of the Ligue 1 campaign.
It is worth taking these rumours with a pinch of salt, however. Real Madrid are known to have financial issues, and it is doubtful that they would be able to afford a £100m fee this summer.
PSG, moreover, have continued to insist that Mbappe is not for sale. Losing the World Cup winner, who is widely considered as a future Ballon d'Or winner, would take the gloss off the Messi signing.
Things could be very different next summer, though. Madrid hope that their history and prestige will appeal to Mbappe, who could be available on a free transfer.
Expect plenty of twists and turns to come...
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