Atletico Madrid forward Antoine Griezmann will have to pay compensation if he does not opt to join Barcelona next summer, according to Sport.
The two clubs have reportedly agreed a "secret pact", detailing the conditions of a proposed transfer and the consequences if it is to fall through.
Should a deal fail to be concluded, Griezmann will be forced to pay compensation to Barcelona, and Barcelona will likewise be required to pay a sum to the player.
The terms of the 26-year-old's potential contract have been agreed, but a transfer fee has not yet been negotiated.
The Blaugrana are attempting to avoid paying Griezmann's full €100m release clause, although Atletico are reluctant to accept a reduced fee.
Sport claim, however, that the deal is all but done regardless of any difficulties in negotiation.
Barcelona are reportedly already considering when to unveil the signing of Griezmann, which is likely to be after this summer's World Cup finals in Russia.
The former Real Sociedad man had previously been strongly linked with a move to Manchester United, but the Red Devils' imminent acquisition of Alexis Sanchez means that they are expected to end their interest.
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Griezmann will, instead, move to Barcelona, if Sport's report is to be believed, where he will join an already formidable attack consisting of Lionel Messi, Luis Suarez, Ousmane Dembele and Philippe Coutinho.