Chelsea have been accused of violating the rules on signing 25 underage players following an investigation by Federation Internationale de Football Association. The number could possibly rise too, with the matter now in the hands of FIFA's disciplinary committee - who do have the power to impose bans as they see fit.
La Liga big guns Barcelona, Real Madrid and Atletico Madrid have all fallen foul of the rules in the past, with all three being handed transfer bans, preventing them from signing players for two consecutive transfer windows, although Real Madrid saw their ban reduced to one window after a successful appeal.
An initial investigation by the world governing body's transfer matching system has suggested that the Blues may have broken rules on the signing of 25 players who were under the age of 18 from overseas. The pictures came to Fifa's attention in January 2016.
The world governing body's rules prohibit global transfers for players under the age of 18, unless their parents emigrate for non-footballing reasons, the player and club are based within 50km of an worldwide border, or the transfer is within the EU or European Economic Area, where the minimum age is 16.
The only other exemption allows for players to be signed within the European Union or a European Economic Area, where the minimum age is 16.More news: Range Resources (NYSE:RRC) Lowered to "Neutral" at Bank of America
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It is within its remit to discard any of the original 25 cases.
The committee can also look into transfers which occurred over the past 10 years, leaving Chelsea quite susceptible to being punished.
It wants the FA to provide facts and figures for the 25 players - and possibly others - such as the registration details and the matches in which they have played.
Federation Internationale de Football Association banned the London club from signing players for two transfer windows in September 2009 due to Gael Kakuta's 2007 move from Lens, a decision which Chelsea successfully appealed at the Court of Arbitration for Sport (CAS).