Arsenal manager Arsene Wenger feels expanding the Champions League to 64 teams would be detrimental to domestic football across Europe.
European football's governing body, UEFA, is considering scrapping the much-maligned Europa League and instead increasing the number of sides in their showpiece competition.
The new format could be introduced for 2015 and might open up the Champions League to as many as seven English clubs and five Scottish teams at a qualifying stage.
Wenger has guided Arsenal into the knockout stages of Europe's elite club tournament for 16 successive seasons, reaching the final in 2006.
And the Gunners boss feels the proposed changes would not be beneficial.
Wenger told Arsenal Player: "I am not convinced because the Champions League already has audience problems in the group stage, I think that would create more and lower the level.
"It would mean that you create a complete European championship league. That could be detrimental to the national leagues as well and could take some interest out of the first stages of the Champions League."
Meanwhile, FIFA have named their three-man short list for the Ballon d'Or, with Barcelona superstar Lionel Messi in contention to land the prestigious accolade for a fourth successive year.
The Argentina forward has netted 82 goals in 2012, just three shy of former West Germany and Bayern Munich striker Gerd Muller's record which was set in 1972.
Real Madrid's Ronaldo, who won the award in 2008, provides strong competition, with Barcelona's Spain playmaker Andres Iniesta completing the nominees.W
enger feels all are worthy. He said: "It's very difficult. For the class, Messi. He's scored 76 goals in one year. It looks just outrageous to me. Therefore it would be one thing to reward something exceptional.
"Ronaldo, has always been there and he deserves it as well. He won the Spanish championship. Iniesta won the European Championship with the national team and, therefore, you could reward him.
"I'm not a big fan of these things - if you judge purely the class, you judge Messi. If you want the achievement of the year, you would choose Ronaldo and maybe Iniesta in second, that is how I see it."