Group stage and play-offs

How many go through

The same competition can answer differently for different events. At Paris 2024, badminton singles groups had three or four players and sent one through. Doubles groups had four pairs and sent two.

The fewer that qualify, the more every group match matters, and the more a single loss can cost. The more that qualify, the more the group stage is about position: who you will meet next, and not whether you survive.

What a high finish buys

Finishing first in a group is rewarded in several different ways.

An easier first opponent. Goalball pairs the pools crosswise for the quarter-finals: first in pool A plays fourth in pool B, and second in B plays third in A. Olympic water polo does the same, 1A against 4B and 2A against 3B. Wrestling does it on a small scale. With two groups, the semi-finals are first in A against second in B, and first in B against second in A. Tug of war uses the same cross when it has two groups, and when it has one, first meets fourth and second meets third.

A round off. In World Curling's play-off system for six teams from one group, the teams ranked first and second go straight to the semi-finals. Teams three to six play qualification games to join them. In its 12-team system, the top four wait in the quarter-finals while teams five to twelve play first.

A second life. In softball's six-team format, the first and second-placed teams play each other, and the loser is not out. It gets one more game, against the winner of third against fourth, for the other place in the final. The third and fourth-placed teams have no such cushion.

A fixed place in the bracket. In para badminton, group winners go to set positions in the knock-out table and the runners-up are drawn into what is left.

Distance from a team you have already played. In the badminton doubles draw at Paris 2024, pairs from the same group were kept apart in the knock-out stage. Para badminton has the same instinct: no runner-up meets the winner of their own group in the first knock-out round. Breaking's manual sends the second of group B against the first of group C, and the second of D against the first of A.

Seeding the knockout again

Some events do not use group position alone. They rank all the qualifiers afresh.

Para ice hockey's regulations reseed the teams for the play-offs and medal games after the preliminary round, by position in the group, then points, then goal difference, then goals scored, then the seeding they came in with. A group winner with a weak record can end up seeded below another group's winner.

Breaking does something similar: the group rankings determine the seeding into the Top 8, with every group winner placed above every runner-up.

Comparing teams from different groups

Sometimes a place goes to "the best second-placed team", or the best third. Those teams never played each other, so the comparison needs its own rule.

Basketball's rules give one. The teams in the same position in each group are put into a notional group of their own and ranked by win-loss record, then points difference, then points scored, then the FIBA ranking.

There is a catch when groups are of different sizes. A team from a group of five has played more games than a team from a group of four. Basketball's answer is to wipe out the results against the last-placed team in the bigger groups, repeating if necessary, until everyone is being compared over the same number of games. The original group standings are not changed by this. Only the comparison is.

Olympic water polo uses a simpler cross-group comparison lower down. The two teams that finish fifth in their groups are classified ninth and tenth by their win-loss record in the group, and if that is the same, by goal average, which the rules define as goals scored divided by games played.

Results that carry forward

A knockout starts everyone level. Some events do not.

The softball World Cups with eight or twelve teams have a Super Round between the groups and the finals. The teams that qualify play the qualifiers from the other group. Their standing then counts those games together with the games they already played against the other qualifiers from their own group. Results against teams that did not qualify are dropped.

So a win in the first week can still be worth something in the second, but only if it was against a team that also went through.

Basketball's rules describe a fuller version. In their example of a tournament in phases, the top three from two groups form a new group "carrying forward their results and classification points", and play only the teams they have not yet met. Sailing's team racing rules set the default the other way: results from an earlier round-robin stage are carried forward only if the event's own documents say so.

The matches change at the join

A group table can absorb a draw. A bracket cannot. So the same sport is played under slightly different rules on either side of the line.

In cerebral palsy football, group matches give three points for a win and one for a draw. In matches "where the tournament structure requires a winning team", extra time is played and then penalties. In Olympic water polo, the rules list the quarter-finals onwards by game number and say they "must be played to a conclusion", by penalty shoot-out if needed.

Ice hockey keeps a winner in every game but changes the overtime: up to five minutes in the preliminary round and up to ten in a play-off.

Placing everyone else

Medals need a final and often a bronze-medal game. Rankings, and the qualification places that depend on them, need more.

Goalball plays it out. The four losing quarter-finalists play again for fifth to eighth place. Olympic water polo does the same, with a full second bracket: the losing quarter-finalists play semi-finals of their own, and then matches for fifth and for seventh. The softball World Cups send the teams that miss the Super Round into a Placement Round.

Curling's rules allow the opposite. Where a single loss eliminates a team and no qualification points are at stake, teams knocked out in the same session are ranked equal.

Tug of war sits between: the two losing semi-finalists have a pull-off for bronze, and nothing is specified below that.

Making the groups fair

A group stage is only as fair as its groups.

At Paris 2024, the seeded players were placed at the top of the groups, one per group, and the rest were drawn in by lot. Players or pairs from the same country could not be drawn in the same group.

Olympic water polo draws teams "by pairs" into its two groups. On the first line are the two best teams from the previous World Championship, and one goes into group A and the other into B. Each following line is another pair of teams of about the same standing, split the same way.

Fencing and breaking lay their ranked entrants across the groups in a snake, described on the round robin page. The 3x3 basketball rules seed national teams into pools by their federation's ranking.

Tug of war fixes the number of groups by the size of the entry: one group for 4 to 11 teams, two for 12 to 22, four for 23 to 44. If withdrawals after the draw leave the groups badly unequal, a new draw may be made.

Above the event: divisions

A group stage sorts teams inside one tournament. Some sports also sort them between tournaments, so that the top event is kept small and the teams in it are well matched.

Para ice hockey's World Championships were set out this way in its 2020-21 regulations. There were three levels, called the A-Pool, the B-Pool and the C-Pool. The A-Pool of 2021 was made up of the top six teams from the 2019 A-Pool and the top two from the 2019 B-Pool. The bottom two A-Pool teams went the other way. A team was promoted from the C-Pool into the B-Pool, and one was relegated from B to C.

That is promotion and relegation in the plain sense: finishing position in one edition decides which level a team plays at in the next. A league with divisions works on the same principle over a season. No league's regulations have been read for this page, so nothing more is said about them here.

What the combination is good at, and what it costs

This section is reasoning from the structure.

The two halves cover each other's weaknesses. The group guarantees everyone several matches and forgives one bad day. The knockout produces a final and a clear winner. Organisers and broadcasters get a known number of matches early and a climax late.

The joins are where the trouble is. A team that has already qualified may have little to play for in its last group match, or may even prefer a particular result because of whom it would meet next. Teams from different groups are compared on records earned against different opponents. And the same team can lose in the group and win the tournament, or go unbeaten in the group and be eliminated in an hour.

It changes from event to event

The one thing to remember: a format line hides three questions. How many go through from each group? What does first place get that second place does not? Do any group results still count afterwards? The answers are in the competition's regulations, under its competition system or method of competition.