How a tennis draw works
Seeding, qualifying and byes, and what they tell you before the tournament starts.
The knockout draw
The main draw holds 128 players and is single elimination: lose once and the tournament is over. That means 7 matches to the title, and at a major every one of them is best of five sets for the men, which is why the winner of a Grand Slam has often spent more than twenty hours on court by the final Sunday.
The draw is not random. The highest-ranked players are seeded, which spreads them across the bracket so that the strongest cannot meet until the later rounds. Everyone else is drawn into the gaps, which is why the sheet is worth reading before a ball is struck: a section with three seeds in it is a very different proposition from a section with one.
Below the main draw sits qualifying, played the week before. Players who come through it arrive with matches already in their legs and are marked with a Q on the sheet. They are frequently more dangerous in the first round than their ranking suggests, because they are the only people in the draw already playing at tournament speed.
Round-robin groups at the season finals
The season finals do not use a knockout draw at all. The eight players who earned the most ranking points across the year are split into two groups of four, and everyone plays everyone inside their group. The top two from each group reach the semi-finals, and only from that point does the tournament become sudden death.
The format has a consequence worth understanding before you watch: a player can lose their opening match and still win the title, and a player can win two matches and go home on games difference. It rewards a good week rather than a single good day, which is the point.
Reading a bracket before it is played
The draw sheet is published a day or two before play and it is worth ten minutes. Look at which quarter each of the top seeds landed in: a quarter with three seeds is much harder than one with a single seed and three qualifiers, and that asymmetry decides more semi-finalists than form does.
Then look for the qualifiers. They have already played two or three matches that week, they are match-sharp, and they are drawn against players who have not hit a competitive ball in days. First-round upsets cluster there.