European football leagues and player unions said on Tuesday they will formally complain to the European Commission about how FIFA adds competitions to congested fixture schedules.
The legal move backs up warnings to FIFA in May by European Leagues and FIFPRO Europe urging a rethink on what they claimed was an "inherently abusive" decision-making process, including to expand the men's World Cup and Club World Cup.
It also follows a European Court of Justice ruling in December which found FIFA and UEFA abused their dominant position as regulator and competition organiser in a case brought by storied clubs that tried to launch a breakaway Super League in 2021.
"Regretfully, FIFA has consistently refused to include national leagues and player unions in its decision-making process," European Leagues and FIFPRO Europe said in a statement.
Football's world body hit back suggesting some leagues in Europe were "acting with commercial self-interest, hypocrisy, and without consideration to everyone else in the world."
The European Commission in Brussels is the executive arm of the 27-nation European Union and can intervene on alleged breaches of competition law.
"FIFA's decisions over the last years have repeatedly favored its own competitions and commercial interests, neglected its responsibilities as a governing body, and harmed the economic interests of national leagues and the welfare of players," European Leagues and FIFPRO Europe said.
"The international match calendar is now beyond saturation and has become unsustainable for national leagues and a risk for the health of players."
FIFA manages the calendar of international games and tournaments which mandates when clubs must release their players called up for national teams.
Top-tier leagues, which shut down their weekend programs for national-team fixtures, have long claimed they were not fully consulted on the latest version that runs to 2030.
"FIFA's calendar is the only instrument ensuring that international football can continue to survive, co-exist, and prosper alongside domestic and continental club football," the governing body said.
The complaint to Brussels, joined by Spain's LaLiga, will claim "FIFA's conduct infringes EU competition law and notably constitutes an abuse of dominance," their statement said.
"This creates a conflict of interest, which, consistent with recent case law of the EU courts, requires FIFA to exercise its regulatory functions in a way that is transparent, objective, non-discriminatory and proportionate."
The first editions of FIFA's revamped men's competitions will be hosted in the United States.
The men's 2026 World Cup will have 48 teams instead of 32, playing 104 total games instead of 64. Players whose teams reach the semifinals will be involved in eight games in a tournament stretching close to six weeks in the U.S., Canada and Mexico.
The U.S. also will host a relaunched Club World Cup next June-July, with 32 teams -- 12 from Europe including Real Madrid, Manchester City and Bayern Munich -- playing a maximum of seven games.
The Champions League run by UEFA also is adding more teams and more games -- 36 each playing at least eight times in a new format -- in the next seasons. That will squeeze more midweek fixture options from domestic and cup organisers.
FIFA noted that European leagues' member clubs often take offseason tours "involving extensive global travel."
"By contrast," FIFA said, its duty was to "protect the overall interests of world football, including the protection of players, everywhere and at all levels of the game."