Long before either player won a major title, Jannik Sinner and Carlos Alcaraz had already been identified as the rivalry to lead men's tennis into the post 'Big Three' landscape.
An electric night at the US Open three years ago was the first real sign why.
"If this match is the future of men's tennis, we are in for a great era ahead," read a tournament tweet after Alcaraz edged a five-set quarter-final thriller that finished at almost 3am local time.
'Sin-caraz' was born.
On Sunday, the pair return to Arthur Ashe Stadium to contest this year's US Open final - the third successive Grand Slam showpiece between them.