It's the last opportunity for three giants of European football soccer clubs still fighting for a European Super League.

Just over a year ago, 12 clubs attempted to form a breakaway league, but it failed almost as soon as it started.

Real Madrid, Barcelona and Juventus have now taken their case to the European Court of Justice in Luxembourg.

Stifling competition?

The three clubs feel that European football's governing body UEFA is in breach of European competition law.

Over the next two days, 15 judges from across the 27 member states will listen to their cases.

From UEFA's perspective, they believe their competition formats, offer the fairest, most inclusive, platform for all countries and not just for the elite clubs.

CGTN Europe spoke to Andrew Warshaw, chief correspondent for Inside World Football

Warshaw said that whatever decision the European Court of Justice makes could have big ramifications.

''It could be huge because if they could persuade the court that under the rules FIFA and UEFA are not allowed to prevent rival organisations from setting up competitions, that could open the floodgates, and that could have a huge impact.''

Echoes of Bosman

Many experts like Andrew Warshaw believe the decision could be the most important since the 1995 Bosman Ruling. 

That changed how players could transfer between clubs and effectively transformed how the football industry worked. This time round it could have a huge bearing on who effectively runs football. 

Any ruling in favour could also be met with resistance. The original format led to a massive backlash from football fans, especially in the English Premier League who felt the closed competition was unfair.

Andrew Warshaw believes both sides could look for a compromise.

''I don't think that either of them will win conclusively, both sides will be wrapped over the knuckles one way or another and then ultimately perhaps the status quo, will be preserved but UEFA maybe has to make adjustments, to deter clubs from forming a super league in the future," he said.

UEFA has already made changes to their Champions League format from 2024, allowing more teams to participate in the competition.

No final decision on the case is expected until next year.