Tennis scoring once allowed a final set to continue indefinitely until somebody led by two games. That rule produced occasional matches of extraordinary length, and its replacement was driven by scheduling rather than by taste.
Open-ended sets create unbounded matches
Because a service game is easier to win than to break, two strong servers can hold repeatedly without either gaining an advantage. The set then extends without limit.
Nothing in the scoring forces a conclusion, so the outcome depends on when one player finally lapses. Duration becomes a function of endurance rather than of skill difference.
The resulting variance is enormous. A match might finish in two hours or continue for many more, and neither outcome could be predicted from the players involved.
Scheduling cannot absorb that variance
Tournaments run multiple courts across fixed sessions, and each match feeds the next. An unexpectedly long match delays everything scheduled behind it.
Broadcasters face the same problem in stronger form, since airtime is bought in blocks. A match that overruns forces coverage of other matches to be abandoned.
Play may also be suspended for darkness, which means a match can be pushed into an additional day. The knock-on effects then multiply through the remaining rounds.
Recovery becomes the deciding factor
A player who wins an extremely long match often arrives at the next round unable to compete at their normal level. The victory effectively removes them from the tournament anyway.
That outcome is unsatisfactory competitively, since a later round is decided by the previous one's length rather than by the players' relative ability.
Medical staff also raise concerns about cumulative load, particularly in heat. Extended play in high temperatures presents risks that scheduling can reasonably avoid.
How the tiebreak preserves the principle
A tiebreak retains the requirement to win by two while capping the mechanism inside a single game. Serve alternates in a pattern designed to neutralise service advantage.
Because both players serve roughly equally within it, the tiebreak measures the same qualities as a set without the same duration. The structure changes while the principle survives.
Different events adopted different thresholds, with some using a longer deciding tiebreak. Variation across competitions persisted for years before broad standardisation.
What was lost in the change
Extremely long matches produced some of the sport's most memorable contests, and their possibility gave every final set an open horizon. That specific drama is gone.
Players also lost a distinctive test of endurance that rewarded a particular kind of competitor. The advantage held by exceptional servers narrowed correspondingly.
The trade was accepted because predictability serves everything built around the sport. Scheduling, broadcasting and player welfare all improved, and the scoring change was the cheapest way to achieve it.
