UEFA's 55 member associations have voted to boycott the World Cup if FIFA goes ahead with its plan to sell stakes in its competitions to private investors.
The decision was made at an emergency meeting held on Thursday, where proposals that FIFA, world football's governing body, announced on Tuesday were discussed.
UEFA, the body that governs European football, had made its opposition clear by issuing two highly critical statements against the plans. Thursday's vote confirmed this strong stance once again.
The boycott would cover all FIFA competitions, including the men's World Cup, women's World Cup and Club World Cup. It would come into effect if FIFA president Gianni Infantino's proposals are approved by the organization's member associations.
The first time this stance could be put to the test will be in October, when the Women's World Cup play-off matches are scheduled.
FIFA President Gianni Infantino's plan aims to attract around £3.1 billion in private investment, with the group of potential investors led by Joshua Kushner, brother of Jared Kushner, son-in-law of US President Donald Trump.
But the idea has sparked a backlash in Europe. UEFA opposes treating a competition with the history and weight of the World Cup as a financial product rather than a global sporting legacy.
In a strong statement, UEFA stressed that "the World Cup is not for sale", warning that European federations will not participate in FIFA competitions if this private ownership model is adopted.
The European institution also criticized the way the project was presented, describing the process as non-transparent and without sufficient consultation with the federations representing world football.
According to UEFA, the entry of private investors into the ownership of FIFA competitions would forever change the way every decision is made in international football.
The clash is not limited to Europe. The Asian confederation has also expressed concern about the way FIFA has prepared this project without broad consultations, while doubts have also been raised by the North American and Caribbean confederation, CONCACAF.
FIFA, on the other hand, is expected to ask its member associations to make a decision on this proposal by September 19. If UEFA maintains its position, world football could face an unprecedented split, with for the first time in history a conflict between FIFA and the European federations threatening the very existence of the current World Cup format.
A battle for power, money and the future of football has begun. And this time, the ball is no longer on the field, but in the offices of world football's leaders.