The changing of the guard in men's tennis has long been on an asymptotic course, getting closer and closer to the inevitable but not quite materialising.

To find the last instance of someone not named Novak Djokovic, Rafael Nadal, or Roger Federer to have won more than one of the four Grand Slam titles in a calendar year, one will have to track back as far as the preceding millennia.

It was the flamboyant American Andre Agassi who pulled the feat off in 1999 before Federer announced his arrival to the wider audience at the Wimbledon in 2003.

Since 2004, only three years – in 2012, 2014, 2020 – saw none win at least two Grand Slams but the 'Big Three' of Federer, Nadal and Djokovic shared an astonishing 65 Grand Slam trophies from an available 79, marking two decades of unparalleled, polarized dominance in the history of the sport.  

While Federer's influence had subdued since 2019 before the Swiss maestro called it quits three years later, Djokovic and Nadal showed little to no signs of slowing down.

The latter, however, had to succumb to a long-held hip injury. The Spanish Matador went on to miss out almost all of last year's action since crashing out from the second round of Australian Open; and that too, as the defending champion.

Djokovic, though, kept the hegemony of the old guards intact as he capped off the year with US Open triumph despite having fallen prey to new sensation Carlos Alcaraz at the Wimbledon in the Grand Slam prior.  

This year, however, could well prove to be an era-defining one, and the Australian Open, beginning tomorrow, is primed to set the tone and boundary conditions to how 2024 could pan out.    

Nadal, meanwhile, is out of the picture for now, after injury got the better of him recently during the Brisbane International Tennis tournament as he was itching for a return to centre stage.

As it stands, in a host of challengers spearheaded by Alcaraz, who won two of the last five Grand Slams after getting off the mark with 2022 US Open, the changing of guard in men's tennis had been reset in motion.

As Djokovic keeps defying age and injury concerns, will he be able to keep stalling the inevitable as he aims to take his Grand Slam haul to an unprecedented 25? In his favour, the Serbian will get to kickstart proceedings from his favourite hunting ground, Melbourne.

This year, he has most likely the last chance to add the lone silverware which remained elusive: an Olympic gold.       

Here's a look at the top candidates who could edge Djokovic and make waves at this Australian Open:

Carlos Alcaraz:

The 20-year-old Spaniard is the youngest man to ascend to world number one, now ranked two.

A serious contender, with six titles in 2023.

Daniil Medvedev:

The 27-year-old Russian, who skipped warm-up events this time to focus on training, is a two-time Australian Open finalist.

The 2021 US Open champion experienced a resurgent 2023 with 66 wins, and returned to world number three.

Jannik Sinner:

The 22-year-old Italian had a breakthrough 2023 with first Masters title and ATP Finals final.

He was instrumental in Italy's Davis Cup victory, helping him in ascending to a career-high world ranking of four.

Alex de Minaur:

The 24-year-old Australian had an impressive start to 2024, defeating Djokovic at the recently concluded United Cup.

Having broken into top 10 ranking, Minaur aims to become the first Australian man to win at home since 1976. 

Women's circuit, too, awaits compelling matchups

On the contrary, the competition in the women's circuit has been open-ended for nearly the past decade, with world number one Iga Swiatek the only player to have won more than one Grand Slam, in 2022, after Angelique Kerber did the same in 2016.  

Along with Swiatek, the presence of defending champion Aryna Sabalenka, Elena Rybakina has set the stage for compelling matchups.

Iga Swiatek:

The four-time Grand Slam champion, yet to go beyond semi-finals at Melbourne Park, had a stellar 2022 season with 37 straight wins, followed by a brief dip. The 22-year-old Polish ended last year on a high note, winning the United Cup.

Aryna Sabalenka:

The 25-year-old Belarusian has been a consistent performer, as evident by the fact that she reached at least the semi-finals in all four Grand Slam tournaments in 2023. She narrowly missed the year-end world number one ranking to Swiatek.

Elena Rybakina:

The world number three kicked off with a strong start to the year. The 24-year-old Kazakh earned an impressive victory in the Brisbane final, dropping just three games against Sabalenka -- the same opponent who denied her Australian Open success last year. 

Coco Gauff:

The 19-year-old had a memorable 2023 as she clinched the US Open, becoming the first American teenager since Serena Williams in 1999 to seal the coveted trophy. The world number four then carried the momentum this year, winning the Auckland Open, allowing her to arrive in Melbourne in full force.