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Europe's leading clubs have played down the prospect of a breakaway from the Champions League but say changes to the competition may be needed to make it more attractive.
The European Clubs' Association (ECA) has announced a review of the Champions League and Europa League with the results due around the end of the year. It has also demanded a seat at the table before any decision by FIFA to expand the World Cup from 32 to 40 teams is taken.
ECA chairman Karl-Heinz Rummenigge said: "I believe both ECA and UEFA are interested in an evolution of the competitions. Stagnation means regression. We have always jointly looked into ways to further develop and improve the competitions. It is important to find a good and balanced solution for everyone involved."
The ECA's senior vice-chairman Umberto Gandini also told a news conference in Paris: "We are starting a review process of the Champions League and working with UEFA to see which improvements we can bring in to have the most attractive football product every year.
"The process will last six to nine months maximum but it is clear we have to take into account all the measures to make it more and more attractive.
"There is not any kind of understanding that we have to change the Champions League. We will listen to the main actors of the competition and UEFA itself and find out what is best. It may be just a slight change to the access list, it may be many aspects of the competition that can be reviewed and adjusted."
The ECA meeting was given an address by UEFA general secretary Gianni Infantino, who is standing for election as FIFA president later this month. The ECA has no vote but gave its backing to Infantino, however the clubs are not happy with his proposal - also in the manifesto of some rivals and a recommendation of FIFA's reform commission - to expand the World Cup.
An ECA statement said: "Once again ECA expresses its disagreement with the possible increase in the number of teams participating in the World Cup from 32 to 40, as proposed by the FIFA reform committee.
"The healthy balance between club and national team football must not be put at risk. The burden imposed on players has reached its limits; all football stakeholders must protect the players, the key element of the game, from physical overload."