Sinner and Tsitsipas lead the outsiders aiming to upset the applecart at US Open
When the next generation of talent failed to dislodge the Big Three of Djokovic, Rafa Nadal and Roger Federer, Alcaraz arrived on the scene and has since won two Grand Slam titles, also grabbing the number one spot in the rankings.
He will be defending his US Open crown but the 20-year-old will not only keep an eye on Djokovic but also the likes of Jannik Sinner, Andrey Rublev and Holger Rune, who have all become Masters winners in the past year.
Sinner is most likely to upset the applecart after the Italian's run to the Canadian Open title this month, winning the biggest trophy of his career in his third Masters 1000 final.
The Italian, who has reached the quarter-finals at all four majors, played on the front foot in Canada, with an aggressive style of tennis helping him beat Matteo Berrettini, Andy Murray and Alex De Minaur.
"For sure, it's a good confidence boost, no? Especially going into the US Open," said 22-year-old Sinner, who dropped just one set en route to the title.
"I feel like for sure the confidence is going to be a little bit higher, but also my expectations are going to be higher.
"I'm also getting stronger physically, I'm growing. And I guess the combination of being fluid and flexible but also getting stronger makes you hit the ball a little bit harder."
Tsitsipas aiming to end year in style
Another contender who has reached two Grand Slam finals but fallen at the final hurdle is former world number three Stefanos Tsitsipas.
Tsitsipas beat De Minaur in a final to win the Los Cabos Open this month. The final was the third of the year for the Greek after losses in Melbourne and Barcelona to Djokovic and Alcaraz.
The world number seven said he was counting on his hardcourt to climb up the rankings.
"My season has been good. I think I played my best tennis at the Australian Open swing," he said ahead of the Canadian Open.
"I have big standards in terms of finishing the year strong, and I want to deliver to that promise of mine.
"I want to finish the year and go on a nice vacation and say that I've tried my best these last few months to maximize as much as I can and have a big impact on the tour at the end of the year."
The title was also his first since splitting with his father-coach Apostolos and replacing him with Mark Philippoussis.
"My father right now, I gave him some time off. He hasn't had time off since I'm 12 years old," Tsitsipas said, adding that parents were prone to getting emotional during matches.
"So I think for him, I think it's very healthy to take some time away from the court and feel refreshed again."