Expanding the World Cup to 48 teams always presented one obvious problem – it was an imperfect number for a tournament.
With 32 teams, the maths was simple – eight groups of four teams, with the top two going through to a last 16, then quarter-finals, semi-finals and a final.
By adding another 16 nations, Fifa had to find a way to get to a symmetrical knockout stage. There was no ideal solution – one which preserved the intensity of the previous format.
The original plan was to create 16 groups of three teams. The two top in each would go through to the last 16.
But there was an issue. Three-team groups meant individual fixtures – and those in the final match would know exactly what they needed to do to qualify. Nations could play for specific results to secure their passage to the knockout rounds.
Fifa, after all, knew all about alleged collusion from the scandal at the 1982 World Cup. Back then, with groups of four, teams did not play their final group matches at the same time.
West Germany faced Austria in the standalone last game. A slender win for the Germans would send both teams through at the expense of Algeria. The match finished 1-0 to West Germany. Algeria went out.
Fifa changed the format so all final fixtures would be played simultaneously, but that would not have been possible with three-team groups.
The climax to the group stage in Qatar was so exciting that Fifa had a rethink. It accepted there must be 12 four-team groups and two matches would be played at the same time to determine who would qualify.
Except for one crucial difference – something that removed much of the jeopardy that made the last World Cup so gripping.
Eight of the third-placed teams must go through for there to be 32 teams in the knockout rounds. It became harder to be knocked out than to progress.
And one issue becomes clear with two matches this week.
First up, Australia play Paraguay in Group D on Thursday (03:00 BST Friday). Then on Saturday it is Austria v Algeria in Group J (03:00 BST Sunday).
The teams are second and third in their groups, and all on three points.
Four points is almost certain to be enough to take one of the eight third-placed qualifying slots. It creates a situation in which the teams could simply play out a draw.
You could argue a game in Group F falls into the same category, with Japan on four points and Sweden on three.
A draw might suit both, but as Japan already have enough points to qualify in third there is no risk involved from a defeat.
It is the same in Group L, too, with Panama on four points and Croatia on three.
BBC News