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.

Teams could, of course, play for specific results before third-placed teams qualified.

Take one incident at Euro 2004, which led to Italy goalkeeper Gianluigi Buffon and Italian federation president Franco Carraro making accusations of match-fixing.

If Sweden-Denmark was a draw and the teams scored at least twice, Italy would finish third because they scored fewer goals in matches between the three sides.

Sweden equalised in the 89th minute. The final score? Sweden 2-2 Denmark.

Uefa insisted there was nothing suspicious about the result.

There is a further twist at this World Cup.

The fixtures for the third-placed teams are determined by which groups provide the qualifiers.

Play early, and you don't have an idea where you will go if you finish third. Play later, and you know what the path looks like.

What does that mean in reality?

The runners-up in Group J will play the winners of Group H - Spain are top of the table right now.

But where will the third-placed team in Group J go? They could play the Group L winners, perhaps England, or Switzerland who finished top of Group B.

Austria and Algeria will know what the last 32 looks like. They could be in a position where finishing third is more favourable than second.

Rather than playing for a draw, Austria might feel they are better off losing and taking up that match.

The weather may yet play a part too.

If there are storms which cause a match to be paused, Fifa says the other game in the group will not be halted.

So, one fixture might be suspended for a couple of hours due to lightning, and when the teams comes back out they know what they need to do to qualify.

If Australia-Paraguay and Austria-Algeria do play out draws there, will probably be questions about the integrity of the format.

But this has been Fifa's choice. The World Cup did not need to be expanded, but it was part of the manifesto on which Gianni Infantino was elected in 2016.

Maybe it will give Infantino a reason to restore the tournament to a perfect number.

Not reducing to 32, but increasing to 64.