How esports tournaments work: brackets, Swiss stages and series

Games, maps and series: what Bo3 means

The basic unit of an esports match is a single game. In a tactical shooter that game is played on one map; in a MOBA it is one battle from start to destroyed base. Single games are a little random, so most meaningful matches are played as a series.

• Bo1 (best of one): one game decides it. Fast, but a single slip can decide the result.
• Bo3 (best of three): the first team to win two games takes the series.
• Bo5 (best of five): first to three. Common for finals and late knockout rounds.

Many events mix lengths. At the 2025 League of Legends World Championship, Riot Games used best-of-one and best-of-three matches in the Swiss stage and best-of-five for every knockout match. Valve's Counter-Strike Major rulebook sets out a similar mix in its Swiss stages: best-of-three when a team can be eliminated or can qualify, best-of-one otherwise.

In map-based games, a series usually opens with a map veto: teams take turns removing and picking maps from the official pool, so each side gets to play somewhere it is comfortable.

Single elimination: lose once and you are out

Single elimination is the classic knockout cup. Teams are paired, the winner of each match goes through and the loser goes home. With eight teams there are three rounds (quarter-finals, semi-finals, final) and seven matches in total. With 16 teams there are four rounds and 15 matches. The rule is simple: you always need one fewer match than there are teams, because every match removes exactly one team.

Strengths: easy to follow, short and dramatic. Every match matters.

Weaknesses: one bad day ends a strong team's tournament, and a tough draw can knock out two favourites early.

That is why top events often use single elimination only for the final stage, after an earlier stage has filtered the field. The 2025 League of Legends World Championship put its eight Swiss-stage qualifiers into a best-of-five knockout. Valve's Major rulebook sends the eight teams that survive its third stage into a single-elimination playoff.

Double elimination: upper bracket, lower bracket, second chance

Double elimination means a team has to lose twice before it is out. The bracket splits into two halves.

• Upper bracket (winners' bracket): everyone starts here. Win and you stay; lose and you drop down.
• Lower bracket (losers' bracket): teams with one loss. Lose here and you are eliminated.
• Grand final: the upper-bracket winner meets the lower-bracket winner.

The format is fairer to strong teams that have one bad series, and it produces more matches, which suits a broadcast. The cost is time: an eight-team double-elimination bracket has 14 or 15 matches rather than seven.

Organisers handle the grand final differently. In some events, the lower-bracket team must win two series in a row (a bracket reset) because the upper-bracket team has not lost yet. In others, the upper-bracket team instead starts the final with a one-game or one-map advantage, and some simply play one series. The rulebook for each event says which applies.

Round robin and leagues: everyone plays everyone

In a round robin, every team plays every other team. The number of matches grows fast: for n teams it is n × (n − 1) ÷ 2. Four teams need six matches; eight teams need 28; ten teams need 45. A double round robin, where teams meet twice, doubles those figures.

Round robins are the backbone of leagues. Regional professional leagues and school and university competitions often use weekly round-robin fixtures to build a table, followed by playoffs for the top finishers.

Because many teams can finish on the same record, rulebooks set tiebreakers. Typical ones include head-to-head results, game or map difference, round difference and, as a last resort, a deciding match. The order varies, so check the specific rulebook.

Strengths: the fairest test of consistency. Weaknesses: long, and late fixtures can be meaningless for teams already safe or already out.

The Swiss system: paired by record

The Swiss system has become the standard group stage at top-tier events because it sits between a knockout and a round robin. Nobody is eliminated for one loss, but nobody has to play the whole field either.

Here is how it typically works with 16 teams:

1. Round one pairs all 16 teams in eight matches.
2. From round two, teams play opponents with the same record: 1–0 teams meet 1–0 teams, 0–1 teams meet 0–1 teams.
3. A team that reaches three wins advances; a team that reaches three losses is eliminated.
4. The stage lasts at most five rounds. Eight teams go through: two at 3–0, three at 3–1 and three at 3–2.

That last split is exactly what Riot Games described for the 2025 League of Legends World Championship. Riot also said teams would avoid repeat match-ups, and teams from the same region would not meet in round one.

Valve's Counter-Strike Major uses the same three-wins, three-losses rule across three successive Swiss stages. It pairs teams using a Buchholz difficulty score: the sum of current wins minus current losses for every opponent a team has faced. A team that has beaten strong opponents is ranked higher and paired accordingly, which removes random draws from later rounds.

Seeding and invitations: how teams get placed

Seeding means ranking teams before an event so that the strongest do not meet too early. A seed is simply a starting position: the first seed is the team considered strongest on paper.

Seeds and invitations come from rankings, previous results or qualifiers:

• Ranking-based invitations: Valve's Major rulebook allocates invitations by region using its own regional standings.
• Open and closed qualifiers: the RLCS Club Championship Kick-Off in London includes 20 directly invited teams and four teams from an open online qualifier, according to its announcement.
• League placement: in league-based circuits such as League of Legends, results in each regional league decide who goes to the world championship and in what position.

Good seeding keeps late rounds competitive. Poor seeding can create a "group of death" where two strong teams meet early. That is one reason Swiss stages pair by record rather than by a fixed draw.

Online qualifiers versus LAN finals

LAN stands for local area network. In esports it means players compete in the same venue, on the same network, rather than from their own homes over the internet.

Most large events combine the two: online qualifiers let anyone with a team try their luck cheaply, and LAN finals bring the survivors together. British Esports Student Champs works this way, with online matches during the season and live LAN grand finals for its Nationals tier.

What changes at a LAN:

• Fair connections: every player has the same low latency, so nobody gains from living nearer a server.
• Controlled equipment: organisers provide or check PCs and consoles, and admins can watch screens in person.
• Rule enforcement: referees are on hand to pause matches, resolve technical problems and confirm results immediately.
• Pressure: a crowd, cameras and stage lighting. Some teams thrive; some struggle.

Online play brings its own rules, such as anti-cheat software, screen-sharing or camera requirements and procedures for disconnections, all set out in the event rulebook.

Reading a bracket like a regular viewer

A few quick checks will tell you what is at stake in any match you tune into.

1. Which stage is this? A Swiss match at 2–2 is effectively a knockout for both teams. A 0–0 opener is not.
2. What is the series length? A Bo1 underdog win is less surprising than a Bo5 one.
3. Upper or lower bracket? In double elimination, a lower-bracket loss ends a team's event; an upper-bracket loss does not.
4. Is there an advantage? Some grand finals give the upper-bracket finalist a head start. The broadcast normally shows it on the scoreboard.
5. Who picked the map? In map-based games, a team winning its opponent's chosen map is often the story of the series.

Terms such as seed, Bo3 and lower bracket are all in our glossary. For which games use these formats at the highest level, see the big esports games.