Knockout tournaments crown a fair winner, but their runner-up may be a fiction
Lose once and you are out. The single-elimination format powers Wimbledon, the FA Cup and the NCAA basketball bracket, and it reliably finds a champion. What it cannot reliably find is the second-best competitor, because the real silver medallist may have been knocked out early by the eventual winner.
The logic is simple. Imagine sorting four numbers through a knockout. If 4 meets 3 first, both 3 and 1 go out in round one and 2 reaches the final, so 2 gets called runner-up even though nobody checked whether 3 beats it. That is why events add extra games like third-place playoffs; the FIFA World Cup has held one since 1934, while the Euros dropped theirs after 1980. Fairly ranking every position really requires a round-robin in which everyone meets everyone.
Organisers use seeding to stop the best entrants colliding early. Standard seeding pairs top with bottom, so in an eight-seed draw it goes 1 against 8, 2 against 7 and so on, as in the World Snooker Championship. Tennis majors seed only 32 of 128 players and place many seeds randomly, which is how world number 33 Florian Mayer drew and lost to top seed Novak Djokovic in the first round of Wimbledon in 2013. The FA Cup skips seeding altogether and leaves it to the draw.
The format's strengths are real: it handles large fields and produces no meaningless matches. Its weaknesses are just as clear. Most entrants play only a few games, luck and seeding can decide outcomes when performance varies, and it struggles with draws. Chess ties are played over several games because draws are common and white has an edge, and football relies on extra time and penalties.
Even the vocabulary varies. English speakers say round of sixteen or, in South Asia, pre-quarterfinals, while French, Spanish, German and many other languages call it the eighth-final. Mathematically, the number of distinct bracket shapes grows fast; five players can already be arranged in three different ways.
Source: Single-elimination tournament
