The FIFA Council has rubber-stamped plans to expand the World Cup to 48 teams from 2026 onwards - but a body representing some of Europe's leading clubs has come out against the expansion.
FIFA president Gianni Infantino's revamp plan received unanimous backing.
Delegates in Zurich were asked to vote on four proposals to change the existing format or stick with the current format of 32 teams.
This is the first time since the 1998 World Cup that changes have been made to the make-up of the tournament.
Infantino's preferred option for change was for a 2026 competition featuring 16 groups of three, with the top two teams in each group advancing to a a 32-team knock-out stage,
The new format will increase the total number of games from 64 to 80 but remain inside a 32-day schedule.
However, the European Club Association has criticised FIFA's plan.
The body representing the interests of clubs such as Manchester United, Chelsea, Bayern Munich, Barcelona and Real Madrid, has blasted the move, claiming it is motivated by political rather than sporting intentions.
A statement from the body, which represents 220 teams across the continent, said: "The European Club Association (ECA) reiterates that it is in principle not in favour of an expanded World Cup.
"We fail to see the merits to changing the current format of 32 that has proven to be the perfect formula from all perspectives. Questionable is also the urgency in reaching such an important decision, with nine years to go until it becomes applicable, without the proper involvement of stakeholders who will be impacted by this change.
"We understand that this decision has been taken based on political reasons rather than sporting ones and under considerable political pressure, something ECA believes is regrettable.
"ECA will analyse in detail the impact and the consequences of the new format and will address the matter at the next meeting of its Executive Board scheduled for the end of January."
There were also options from FIFA to have a 40-team tournament, with 10 groups of four or eight groups of five, but the only other 48-team make-up would see a 32-team one-game knockout round with the winners joining 16 already-qualified teams.
Infantino has also suggested that penalty shoot-outs be brought in to settle the results of all drawn games, thereby minimising the risk of teams colluding in their final group games to eliminate others from the tournament.
The Swiss has repeatedly said his main motivation for expansion is to give more nations a chance of experiencing the joy of a World Cup, which will bolster international football in developed markets and help its growth in new ones.
More details will be announced at the conclusion of Tuesday's meeting - although the allocation of the extra 16 qualification slots under the new format was not expected to be resolved at this point.
The African and Asian nations are expecting significant increases on their current allocation of four spots apiece.
The other major decision regarding 2026 - who will host the event - is not scheduled for consideration until 2020 with a bid featuring the United States, either on its own or in conjunction with one or both of Canada and Mexico, the overwhelming favourite.