On an unremarkable clay tennis court in the Spanish city of Alicante, watched on by only a handful of spectators, two teenagers swipe the ball to one another with surprising vigor, belying their scrawny, adolescent frames.

The ages of each player – one 17, the other just 15 – suggest that this is unlike most other matches on the ATP’s Challenger Tour, a stepping-stone circuit for those looking to join tennis’ elite.

Over the course of three back-and-forth sets, it’s the younger protagonist who emerges victorious after an hour and 50 minutes. His name is Carlos Alcaraz , and his opponent? Another future world No. 1 named Jannik Sinner .

This match took place more than six years ago, the first meeting of a rivalry which now looks destined to define the current era of men’s tennis.

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