Argentina international Ricky Alvarez remains in limbo following the collapse of his move from Inter Milan to Sunderland.
Governing body FIFA has been called in to arbitrate after Sunderland failed to activate an permanent £8 million transfer clause negotiated as part of the season-long loan deal struck between the two clubs in August last year.
Sunderland pulled the plug on the deal after Inter delayed in granting permission for the now 27-year-old to undergo knee surgery, meaning he was able to make only 17 appearances for the club last season.
However, the matter is yet to be resolved, with a FIFA spokesperson telling Press Association Sport: "Since the investigation is ongoing, we are not in a position to comment on it any further, nor to give an estimation of the timeline."
Under the terms of the agreement, Sunderland were duty-bound to go ahead with the transfer if they retained their Premier League status at the end of last season, which they did courtesy of another late run under head coach Dick Advocaat.
The Dutchman had replaced Gus Poyet, the man in charge when Alvarez was signed, in March.
However, Sunderland's view is that Inter were in breach of the loan contract because of their stance on Alvarez's knee problem.
There appeared to be some light at the end of the tunnel for the midfielder when it was reported that Argentine club San Lorenzo had expressed an interest in signing him.
However, the impasse in his situation appears to have ended that possibility, in the short term at least.
The FIFA spokesperson added: "We can confirm that FIFA was contacted by the Argentinian Football Association with respect to the possible registration of the player with one of their affiliated clubs.
"Our services replied by referring them to the applicable procedure and the relevant provisions of the pertinent regulations."