UEFA president Aleksander Ceferin has warned of a potential European boycott of the World Cup if FIFA's plans to stage the tournament every two years go ahead.
World football's governing body is carrying out a review of the international match calendar, led by former longtime Arsenal manager Arsene Wenger, who is proposing a major tournament every year.
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Under the proposals, the World Cup would rotate with continental tournaments such as the European Championship and be played every two years instead of every four.
"We can decide not to play in it," Ceferin told The Times.
"As far as I know, the South Americans are on the same page. So good luck with a World Cup like that. I think it will never happen as it is so much against the basic principles of football.
"To play every summer a one-month tournament, for the players it's a killer. If it's every two years it clashes with the women's World Cup, with the Olympic football tournament.
"The value is precisely because it is every four years, you wait for it, it's like the Olympic Games, it's a huge event. I don't see our federations supporting that."
However, FIFA's plan to hold the World Cup every two years has received a "very positive response," Wenger said on Thursday.
Former Brazil striker Ronaldo appeared on a virtual news conference with Wenger and expressed his support for the idea with ex-Australia international Tim Cahill and former Denmark goalkeeper Peter Schmeichel also backing the process.
Schmeichel said that none of the players who had attended the discussion had been against the idea of moving to a two-year cycle.
"Overall, I think I have got a very positive response, but this decision is a democratic decision and will be made certainly by the 211 countries who are affiliated to FIFA. I think that we continue to consult people," Wenger said.
The Frenchman's plans have also been opposed by World Leagues Forum and European Leagues, which represents professional club competitions in their respective regions.
Asked about that opposition and the risk of major conflict within the game, Wenger said he was just carrying out the role of developing a solution for the game.
"I'm not hesitant at all. I'm 100% convinced that what I propose is the right solution for the modern way to organise football. If people have better ideas, I'm open to it and I welcome every idea that is better than mine," he said.
"I will not vote. I just make a proposal that I think will improve things and make life better for everybody, but especially make football better."
Wenger added that his role was to convince people of the merits of his proposal. He also said a decision on the next steps for the proposal could be taken by FIFA as early as December.
LaLiga president Javier Tebas is the latest European football figure to come out against the plans.
"A biennial World Cup is a threat not just to domestic football leagues but to the overall tradition of world football," he said.
"It would require a reshuffle of the calendar that would disrupt the domestic leagues to the extent that interest would be lost and the continuity is jeopardised.
"This would have a cascading effect on the entire football pyramid, with fans losing interest in the sport. New competitions or playing more often will not help grow football, to the contrary.