Tennis: the draw decides more than the ranking does

Four tournaments a year carry the designation, they award identical ranking points, and each runs a 128-player singles draw over seven rounds. That structure is unusual in professional sport: no group stage, no second chances, and a single defeat at any point ends the tournament. Everything about how these markets behave follows from the fact that a title requires seven consecutive wins.

The men's event is played over best of five sets, which is the longest format any of these players contest all year. Longer matches reduce variance, and reduced variance favours the stronger player - a favourite who wins 60 per cent of points wins a best-of-five far more often than a best-of-three. That is why Grand Slam favourites trade at prices that would look extreme at a regular tour event, and it is a real effect rather than sentiment.

The rankings decide entry and seeding rather than the outcome. They count a player's best results over a rolling period - eighteen of them from the week of 29 December 2025, reduced from nineteen - which makes them a measure of accumulated consistency rather than of current form. A player returning from injury can be dangerous and unseeded at the same time, and that combination is the single most common way a draw turns out to be harder than it looked.

The board carries both tournament-winner markets and individual match markets, including qualifying rounds, and they are different instruments. A winner market is a compounding question - seven wins, each conditional on the last - and it resolves over a fortnight. A match market is a single event resolving within hours, priced off form, surface and matchup rather than off path.

The winner market's key property is that it is a product of conditional probabilities, which makes it far more sensitive to the draw than intuition suggests. A favourite who must beat two top-ten players to reach the final has a materially lower title probability than one with an easier quarter, even if their true strength is identical. The draw is published before the tournament begins, and the market frequently takes a day to fully absorb it.

Match markets in qualifying rounds are the thinnest and most volatile end. Qualifying draws feature players whose recent form is poorly documented and who may be carrying injuries not publicly known, and volumes are large relative to how much reliable information exists. That combination is where the retirement rules below matter most.

The distinction between a walkover and a retirement is the most important settlement fact in this subject, and it turns on a single moment. A walkover occurs after the draw is finalised but before the first serve of the match; once that first serve has been struck, any withdrawal is a retirement instead. Same player, same injury, same outcome on court - two different categories, and venue rules routinely treat them differently.

That matters because the two are handled differently almost everywhere. A walkover commonly voids a match market entirely, since no match took place; a retirement usually resolves in favour of the player who did not retire, or requires a set to have been completed first. A contract that does not say which rule it follows is carrying an unpriced risk that materialises several times per Grand Slam.

Everything else in this subject is exceptionally well documented. The governing rulebook is published, the draws are public, ranking points are published per round and are identical across the four Slams, and the order of play is released daily. For a sport, the primary sources here are unusually complete - which makes the retirement rule's obscurity all the more expensive.