Boca Juniors are trying to renegotiate the price for the defender after a failed medical.
The defender is expected to leave the Stadium of Light this summer, as he is not a part of manager Sam Allardyce’s plans.
A move to Boca Juniors has already been agreed, with the player even donning a Boca shirt ahead of his unveiling by the Argentinian club.
However, reports in the country over the weekend claimed that he had failed a medical because of a problem with his Achilles.
That had led to suggestions that the move was now off, but the Sunderland Echo reports that it is still on track.
According to them, the injury is only a minor one and instead of the deal being cancelled, Boca are now attempting to renegotiate the terms of the transfer.
They are attempting to knock down Sunderland’s asking price, but as far as the Echo is concerned they will be unsuccessful in that attempt.
The Black Cats are confident they can recoup the bulk of the £2 million the paid for him last summer and are not willing to move on their asking price.