In the FIFA World Cup, the 32 national teams are allocated to eight groups of four, where the top two teams qualify for the Round of 16. Therefore, it is important to balance the difficulty levels of the groups: if a group contains three strong teams, at least one of them will be eliminated in the group stage. The draw system used until 2014 has been subject to considerable criticism over the years, hence FIFA adopted one recommendation of a French mathematician, Julien Guyon, for the 2018 World Cup draw.