20 teams: 4 groups of 5, then a playoff

Why 4 groups of 5

Pools of at most five, and never fewer than two pools — that is the rule, and for 20 teams it comes out at 4 groups of 5. Groups of four or five are the sweet spot: three or four guaranteed matches each, and a table small enough to be final before the playoff needs it.

20 divides evenly, so every group is the same size and every team plays the same number of group matches. Nothing has to be adjusted for fairness.

The playoff is drawn before the groups are played

8 teams qualify — the top two of each group — which fills quarter-finals. The bracket is drawn at the same time as the groups, with its positions labelled "1. A", "2. B" and so on, so the whole day is on the wall from the first whistle.

As each group finishes, the positions waiting on it resolve and the real names appear. A group table is provisional until every fixture in it is settled, and a playoff position will not fill from a provisional table — a team told they are through while a match that changes the order is still on the next court is the worst thing this could get wrong.

How long the day is

48 matches: the group matches, plus the 8 of the playoff including a third-place match. The group stage parallelises well across courts; the playoff does not, because each round waits for the one before it.

Common questions