The UEFA-recognized Football Supporters Europe group stepped up its opposition ahead of upcoming meetings involving the European Club Association and UEFA.
Proposals were agreed to last year to use clubs' historical record in European competitions to award two Champions League entries in 2024 when it would expand to 36 teams playing 10 games each instead of six.
But UEFA reached that deal with leaders of clubs as they were plotting to launch the Super League project which quickly failed, and the details were open to be revisited.
The FSE fan group now wants those details _ the historical ``coefficient'' entries and 10 guaranteed games _ to be overturned Tuesday after the UEFA club competitions committee and executive committee meet in Vienna, Austria.
``In the end, your decision will shape the game for a generation impacting every league, club, player and fan in Europe,'' the FSE said in a statement targeting UEFA and ECA officials.
The 250-member ECA, whose board meets Monday in Madrid, and UEFA have not officially commented on talks that could lead to decisions on Tuesday.
Entries to the Champions League are set to be worth tens of millions of euros (dollars) to each club taking part with forecasts of about 40% rise in total revenue for UEFA club competitions starting in 2024.
Fans fear Champions League money will further widen the wealth and competitive balance gaps in European soccer, reduce interest in domestic leagues and adds costs in time and money for supporters to follow their team.
The 30-nation European Leagues group and fans have consistently said extra entries in the Champions League should instead go to title winners in mid-ranking national leagues.
Opposition to the agreed changes has been joined on behalf of ``middle-class'' clubs by Eintracht Frankfurt, which advanced last week to the final of the Europa League against Rangers. The winner gets a Champions League place.
UEFA has also considered scrapping traditional two-leg semifinals in favor of a Final Four-type mini tournament of single games in one host city or region.
The FSE dismissed such ideas as ``juvenile daydreams of extended halftime shows, week-long finals and similar Super Bowl knockoffs.''
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