According to a report from Brazilian newspaper O Tempo, Chelsea attacker Nathan will indeed be staying with his previous loan club, Atlético Mineiro, as all parties involved have wanted for a while, but only on loan (again) once he extends his current Chelsea contract.
Nathan’s current contract is set to end in June, theoretically allowing him to arrange terms for a free transfer for the summer. But by then the Brazilian season will have been half over. And so, since Atlético are cash-strapped and are apparently unable to arrange a transfer at this time, they are hoping to keep Nathan on loan for the next six months at least.
Meanwhile, signing an extension should enable Chelsea to collect some sort of transfer fee eventually, either from Atlético or whoever else may be interested and willing to pay.
By the summer, Atlético are expected to have the funds to complete the transfer. But since this is Brazil, and clubs here not exactly known for sound financial management, we can expect another drawn-out saga on this front.