5 potential future rivals for Jannik Sinner & Carlos Alcaraz: ft. Fonseca, Mensik, Fils
Who can challenge Carlos Alcaraz and Jannik Sinner?
That is the question many are asking, with the two multiple-time Grand Slam champions dominating the sport in recent months.
World No 1 Sinner and No 2 Alcaraz have split the last seven Grand Slam tournaments between them, with no clear rival to them yet.
Here, we look at five ATP Tour rising stars who could be among those looking to rival them in the future.
Holger Rune
Rune’s career has somewhat stalled in recent years, but the Dane is only 22 – so is time still on his side?
The advantage Rune may have is that he has already reached world No 4 and won a Masters 1000 title at the Paris Indoors in 2022, meaning he has some experience of competing at a high level.
A three-time Grand Slam quarter-finalist, the 2022 year has struggled to push on since his breakout 2022 and 2023 campaigns, though he beat Alcaraz to lift the Barcelona Open title in April.
The Dane was also an Indian Wells finalist this year and has returned to the top 10 of the ATP Rankings, with tennis icon Andre Agassi now a key mentor for him.
Rune’s potential has long been known, but has he left it too long to rival Alcaraz and Sinner – or is the best yet to come?
Jakub Mensik
Mensik soared up the ATP Rankings in 2024 and has continued to progress leaps and bounds in 2025.
The standout moment of his career so far was undoubtedly his run to the Miami Open title back in March, not only his first Masters 1000 title, but a first ATP-level title full stop.
The 19-year-old surged inside the top 25 for the first time thanks to that triumph, and is now at a career-high of world No 17 after some solid results post-Miami.
A strong Grand Slam run is perhaps the biggest thing the Czech is missing, with Mensik yet to make it past round three of a major after several tough major losses in recent months.
But, with a big serve and impressively clean ballstriking, Mensik looks set to be a significant factor for many years.
Arthur Fils
The injury Fils sustained at the French Open back in May has seemingly disrupted the Frenchman’s momentum, with the 21-year-old having fallen back out of the top 20 as a result.
However, there is no doubt that he has been one of the most eye-catching performers of recent months, with two notable ATP 500 titles in Hamburg and Tokyo heading his way last year.
Fils also reached the quarter-final of the first three Masters 1000 events of this season, becoming the youngest man to do that since 1990, and was as high as world No 14 in April before his back issue.
The Frenchman has one of the biggest forehands in the sport and is certainly not lacking in self-belief, though, like Mensik, he has struggled to make his mark at Grand Slams.
Tennis News
Jannik Sinner’s coaching surprise ahead of US Open
Elena Rybakina reveals Jannik Sinner, Carlos Alcaraz US Open wish ahead of mixed doubles campaign
Fitness has at times been an issue, but once he returns to court, he will certainly be one to watch in the future.
Joao Fonseca
Teen sensation Fonseca was dubbed the ‘next challenger’ to Alcaraz and Sinner’s dominance last week, and it is easy to see why there is so much hype around the Brazilian.
Fonseca is still only 18 but has already won an ATP Tour title, triumphing at the Argentina Open back in February, and cracked the top 50 of the ATP Rankings after reaching the third round of Wimbledon.
That run on his SW19 debut came after impressive campaigns at the Australian Open and Roland Garros, and the Brazilian appears to have a maturity beyond his years when it comes to expectations on him.
Fonseca only turns 19 in August, meaning there is probably a good couple of years yet until he is potentially at the top of the game.
However, with a huge forehand, incredible improvement, and a run of continued improvement behind him, it is hard not to see him competing for major titles in the future.
Learner Tien
World No 67 Tien has played five matches against top-10 opponents in 2025, and has won four of them.
The American lost to Alexander Zverev at Roland Garros but beat the German in Acapulco, with a standout win over Daniil Medvedev back at the Australian Open in January.
Further wins over Ben Shelton and Andrey Rublev have cemented the 19-year-old’s place as one to watch in the future, and all eyes will be on how he fares this hard-court swing.
Tien does not play with huge power, but holds a tactical awareness well beyond his years, and is already able to deal with a range of different opponents without appearing fazed.
He is yet to face either Alcaraz or Sinner, though he could be with them towards the top of the sport in the next few seasons.
Read Next: 2025 ATP Canadian Open: How much prize money and points are on offer? When is the draw?
