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Tennis scoring, explained: why 15, 30, 40 and deuce
In one line: Love, 15, 30, 40, deuce, advantage: the strangest scoring system in sport decoded, plus sets, tie-breaks and why matches never end on time.
Fifteen, thirty, forty, love, deuce, ad-in, ad-out: tennis scoring sounds like a card game read aloud by a butler. It is actually a small, coherent machine — once decoded, it explains why tennis produces more drama per point than almost any sport.
Points, games, sets: the three-layer clock
A game is won by the first player to four points with a two-point margin — the points are called love (zero), 15, 30 and 40 (the folk etymology — a clock face quartered, "quarante-cinq" corrupted — is unproven but harmless). At 40–40, deuce, the two-point margin rule takes over: win one and you hold advantage; win the next and the game is yours; lose it and it is deuce again. Six games with a two-game margin wins a set; at 6–6 a tie-break usually decides it — first to seven points, same margin rule. Best of three sets wins most matches; the Grand Slams play men best of five, which is why a Slam match can run five hours while a tour final finishes in ninety minutes.
Why the system makes drama
The two-point margin rules — deuce, and the 6–6 tie-break — exist to stop games and sets dragging forever, but they create something no other scoring system does: every single point can be decisive. Break point, set point, match point — a player 40–0 down in the final game of the final set is one point from disaster, and the scoreboard says so out loud. Because service alternates every game, matches have no clock: a match ends when the tennis ends, which is why schedules run late and why tennis produces comebacks that timed sports structurally prevent.
The quirks, briefly
Serve alternates each game; ends change on odd games; the deciding set at Slams now uses a ten-point tie-break at 6–6 (recently standardised after decades of marathons, including the 11–9 fifth set at Wimbledon 2010 that ran over eleven hours across three days). Doubles often replaces the deciding point with a "golden point" and the third set with a match tie-break. And the chair umpire's vocabulary — "advantage, server" — is simply the margin rule narrated.
The one-line decoder: tennis is a game of games of sets, and every layer insists on winning by two — which is exactly why a match can hinge on a single shot, and why the scoring, for all its medieval flavour, has never been seriously challenged.
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