Manchester City could be hit with a transfer ban if they lose a case being heard by the Court of Arbitration for Sport on Monday.
Argentine club Velez Sarsfield say City broke rules when 16-year-old midfielder Benjamin Garre joined the Premier League club last year.
In September, FIFA upheld City’s argument that Garre holds an Italian passport and was therefore free to join them after his 16th birthday.
The CAS decision may not be known for several weeks, but City face the threat of being banned from registering players for the next two transfer windows if it goes against them.