Nail-Biting Index: A data-driven measure of tennis match drama

Tennis fans fall victim to recency bias—claiming every new five-setter is "the greatest match ever." The Nail-Biting Index cuts through the noise by measuring actual drama through comebacks, tiebreaks, and clutch play. Some iconic matches barely register, while forgotten battles from the past prove statistically more dramatic.

Rank Match Tournament Round Score NBI Drama Tags

The NBI Formula

NBI = 0.25 × (Set Closeness) + 0.22 × (Comeback Factor) + 0.18 × (Lead Changes) + 0.12 × (Tiebreak Count) + 0.10 × (Match Duration) + 0.07 × (Break Point Drama) + 0.06 × (Final Set Tiebreak)

Set Closeness

Measures how close each set was—smaller average margins mean tighter, more competitive sets.

25%

Comeback Factor

Rewards matches where a player comes back from a significant deficit, especially from two sets down.

22%

Lead Changes

Counts how often the match momentum shifted, showing back-and-forth battles.

18%

Tiebreak Count

Number of sets decided by a tiebreak, highlighting high-pressure moments.

12%

Match Duration

Normalizes match length per set—longer, drawn-out battles score higher.

10%

Break Point Drama

Reflects the share of break points saved, emphasizing clutch play under pressure.

7%

Final Set Tiebreak

Indicates if the match was decided by a tiebreak in the final set.

6%