Deciding sets once ran until a player led by two games, occasionally producing matches that lasted beyond a single day. Every major has since adopted a tiebreak ending, and the reasons are structural rather than aesthetic.
The old rule had no upper bound
A set requires six games and a two-game margin. A deciding set without a tiebreak simply repeats that requirement until one player finally achieves it.
Serving is an advantage at professional level, and on fast surfaces the advantage grows. When both players hold routinely, the break needed to end the set may never arrive.
The result was a handful of matches running to scores no scheduler had planned for. They were memorable, and they were also a genuine operational problem.
Scheduling is the binding constraint
A grand slam runs dozens of matches a day across a limited number of courts. Each court holds one match at a time, so an overrun pushes everything behind it.
Broadcast windows compound this, because television contracts assume matches finish within a predictable range. An open-ended set makes that range impossible to state in advance.
Players waiting to start are affected too, warming up repeatedly and eating at uncertain times. The cost of one long match spreads across many competitors.
Player welfare pushed the same way
A match running hours beyond normal length leaves the winner with recovery time the tournament cannot extend. The next round arrives on schedule regardless.
A player who survives a marathon often reaches the following match unable to move properly, which turns a great contest into a poor one. The reward for winning becomes a penalty.
Governing bodies weighed that against the drama of an unlimited set and decided the trade was not worth making. A tiebreak caps the physical cost at a known ceiling.
The majors did not converge immediately
Each tournament experimented separately, and for several years the deciding-set rule depended on which event a player had entered. Some used a tiebreak at a raised game score.
That inconsistency created its own difficulty, because late-set tactics depend on knowing when the set can end. Players were effectively learning four different endings.
The eventual settlement on a common rule removed the confusion, though it also removed a piece of each tournament's distinct character.
What the tiebreak changes about play
A tiebreak compresses the decisive phase into a handful of points, raising the value of the serve and of a single mini-break. Errors absorbed over several games become final.
Players approach the closing stages differently, conserving energy earlier because the end is now in sight. The rhythm of a deciding set is not what it was.
Whether that produces better tennis is arguable. It certainly produces more predictable tennis, which is what a tournament running to a fixed calendar requires.
