An epoch-shifting Grand Slam season dominated by Jannik Sinner and Carlos Alcaraz has provided the clearest sign yet that the "Big Three" era of men's tennis is finally over, with Novak Djokovic destined to be its last year-end number one.

The golden rule that you should never write off Djokovic still holds true, but after he, Rafa Nadal and Roger Federer had won at least one Grand Slam title between them every season since 2003, this year there were none.

Sinner lifted the U.S. Open title on Sunday following his breakthrough Australian Open triumph in January, while Alcaraz won the French Open and Wimbledon to mark the first time since 1993 that men aged 23 or under had swept the Grand Slams.