In the latest edition of Second Serve, our weekly snapshot of the tours, BBC tennis reporter Jonathan Jurejko discusses the rivalry between Jannik Sinner and Carlos Alcaraz.
There are a number of factors which turn an exciting rivalry into an epic, enduring duel that transcends the sport.
The core talent. The blend of personalities. The gripping encounters on the biggest stages.
The tussle between Jannik Sinner and Carlos Alcaraz - ranked one and two in the men's game - has all those components.