UEFA has opened disciplinary proceedings against the three clubs yet to disavow themselves of The Super League project.
Barcelona, Juventus and Real Madrid are the only three of the original twelve clubs clinging to the proposal of a breakaway European competition.
The others - including the Premier League's so-called 'big 6' - have all recently reaffirmed their commitment to the existing UEFA competitions.
UEFA president Aleksander Ceferin warned the remaining holdouts last month that they could face bans from the Champions League.
"It’s crystal clear that the clubs will have to decide if they are Super League or they are a European club," he told AP.
"If they say we are a Super League, then they don’t play Champions League, of course ... and if they are ready to do that, they can play in their own competition.”
While conceding the recent iteration of the Super League is unlikely to proceed, Barcelona president Joan Laporta insisted that something similar is "absolutely necessary".
Incidentally, Barça recently secured a €500million loan from Goldman Sachs to help service the club's debt. Their gross debt stands at €1.173billion, with €730million of that due to be serviced in the short term.
Real's financial picture is no rosier, with their gross debts standing at €901million.
A Champions League ban would hurt all three clubs financially, and it appears that prospect is a live one.
"Following an investigation conducted by UEFA Ethics and Disciplinary Inspectors in connection with the so-called ‘Super League’ project, disciplinary proceedings have been opened against Real Madrid, Barcelona & Juventus for a potential violation of UEFA’s legal framework," a statement read on Tuesday evening.