FIFA has announced an increase in the number of teams at the World Cup from 32 to 48 teams.
The football governing body says the move will see 16 groups of 3 teams each.
However the move will be implemented from the 2026 World Cup.
With the new format, an initial stage of 16 groups of three teams will precede a knockout stage for the remaining 32 when the change is made for the 2026 tournament.
The number of tournament matches will rise to 80, from 64, but the eventual winners will still play only seven games.
The tournament will be completed within 32 days – a measure to appease European clubs, who objected to reform because of a crowded international schedule.
The next World Cup is the 2018 World Cup which will be held in Russia.