Men's tennis has, for the last decade and a half, been absolutely dominated by the 'big three' of Roger Federer, Rafael Nadal and Novak Djokovic.
It has been the most sensational era to watch, with arguably the three best players arriving and competing at the same time.
However, all three are nearing the end of their careers now, and tennis has to look to the next generation for its poster boys.
And, in Carlos Alcaraz, Lorenzo Musetti and Jannik Sinner, the ATP may have a ready-made trio able to step into the breach.
The Warrior: Carlos Alcaraz
It's easy, perhaps too easy, to make comparisons between Rafael Nadal and Carlos Alcaraz.
In fact, people have been aware of Alcaraz and his talent since he was 15, and from that moment he has had to endure the 'new Rafael Nadal' moniker.
He himself has always distanced himself from comparisons, and rightly so. They obviously are not helpful, but they are also not especially accurate either.
Their games are quite different when you drill down into them, but they do share one striking similarity, and that is they are both incredible warriors on the court.
In fairness, it is a trait that most Spanish players seem to share. They are renowned for two things really: prowess on clay and supreme grit.
Alcaraz has already shown he is a true warrior on the court, no more so than when he faced Nadal himself in the semi-finals of Indian Wells.
The youngster ended up losing the match, but it was such hard work to beat him that Nadal ended up injuring himself in the process.
Looking ahead, it is almost impossible to see Alcaraz not going on and becoming a multiple major winner. He will probably not win the 21 (and counting) that Nadal has, but the talent is there.
Plus, despite Alcaraz being only 19 years old, he is already at a level where he will be able to realistically compete for any title in men's tennis, and that is remarkable in itself.
The Artist: Lorenzo Musetti
Lorenzo Musetti is developing slower than many would have liked to see, but there has not been a talent like him for some time on the ATP Tour.
Musetti is 20 years old so you would expect him to be further along than Alcaraz, but while Alcaraz has developed physically at an early age and relies on a power game, Musetti is a touch player - and finesse takes longer to perfect.
In that sense alone the Italian is reminiscent of Roger Federer, who was a year or two older than Rafael Nadal was when they started winning everything.
That is not the only similarity either. For starters, Musetti, like Federer, has an elegant one-handed backhand in an age when the two-handed alternative dominates.
He is also a genuine shot-maker, always looking to attack and go for the big shots and winners. That was something that always set Federer apart from the more defence-minded Nadal and Djokovic.
Musetti is the one out of the three who has charisma in droves too. He has the looks and has already featured as the cover-star on men's fashion magazines. He says if he couldn't have been a tennis player, he would have been an actor instead, such is his comfort in the limelight.
Of the three players featured here, Musetti is the one who you feel could still go either way in terms of his future.
At the moment he is just not patient enough and wants to go for his big winners all the time. That leads to too many unforced errors and then onto frustration, which in turn diminishes his patience even more.
However, if he can learn the patience to properly construct his points before unleashing his weapons, Musetti will become an enormous draw in tennis for many years.
Certainly, compatriot Jannik Sinner sees the talent, with him saying of Musetti: "He hits the ball very hard, he is very good at moving it, at changing. He is perhaps now a better player than me."
The Machine: Jannik Sinner
Whenever you describe Novak Djokovic as a 'machine' or 'robot' you are risking criticism from his legion of devoted fans who see him as considerably more than that.
That is a reasonable position to take too. Djokovic is actually one of the most emotional and passionate players on the ATP Tour, and definitely one of the biggest personalities too.
In this sense, we absolutely mean 'machine' as nothing but a compliment, though. Playing Djokovic is often like playing tennis against a brick wall in the sense that the ball always seems to be returned to you from the baseline no matter what you do.
While the GOAT debate is a constant and contentious one, no one will surely argue with an assertion that Novak Djokovic is the greatest power baseline player that tennis has ever seen, and Jannik Sinner is someone who's game seems very similar to the Serb's.
Sinner was a champion skier in his youth, and he has transferred that incredible balance to the tennis court to become one of the most agile and mobile players around.
He combines that with some supremely clean hitting from the baseline and together they can often be overwhelming for opposing players.
Sinner, another Italian, is 20 years old and has already debuted in the top ten, as well as made an appearance at the Tour Finals, albeit as an alternate.
Djokovic, as a package, perhaps can never be replicated. He is a unique product of an upbringing in a war-torn country and natural talent forged in the fires of the most competitive era in men's tennis history.
Sinner is the closest we have seen to Djokovic in terms of his actual game, though, and he looks absolutely destined to win multiple majors before he is done in the game.