Barcelona star Neymar reportedly intended to join Manchester United in a world-record deal last summer, but the move broke down.
The Brazilian attacker is believed to be on the verge of becoming the most expensive player in the world, with Paris Saint-Germain willing to pay a €222m (£196m) release clause.
Barcelona confirmed on Wednesday that Neymar has informed the club that he wants to leave, and that he has been granted permission to "resolve his future".
According to L'Equipe, if things had gone to plan last summer, the prolific forward would be a United player now as he agreed personal terms with the Premier League giants before the transfer fell through.
Meanwhile, Barca star Lionel Messi has bid farewell to his teammate on social media.
