The main knock-on effect is a greater chance of teams not only advancing but winning the group before matchday three.

Under the old format, a team would need to be four points clear of second to lock top spot after two games.

That was rare because it required the other two fixtures of the first two rounds in the group to both be draws.

Now it is possible to be three points clear and get first place in the bag.

It can happen a few ways.

It requires either two draws, or first place to have beaten the team(s) on three points.

We have already seen it in Group A.

Mexico won their first two games and sit on six points - three points clear of South Korea, with the Czech Republic and South Africa on one point.

As Mexico have already beaten South Korea they cannot be overtaken if both countries end on six points. So Mexico have won the group.

They know they will play a last-32 tie in Mexico City against a third-placed team.

But there's a knock-on effect.

Mexico effectively have nothing to play for when they meet the Czech Republic next Wednesday, and could opt to rest players.

And that creates an imbalance the Czech Republic could benefit from, though they can only qualify automatically if South Korea lose to South Africa.

But in a tournament where the best third-placed teams go through, it could be important.

The system is also used at the European Championship, where the best third-placed teams advanced.