Who will challenge Sincaraz?

 

The kids coming for Sinner and Alcaraz

Sinner and Alcaraz have quietly turned the top of the men's game into a two-man rotation. They've split the last several slams between them. Most big finals lately have one of them in it. Sometimes both. It's been fun to watch, but it's starting to feel like a show waiting for a third character.

So who's the third character?

I've been watching the under-22 crop closely this year, and a few names are actually worth caring about.

Fonseca and Tien: two ways to come at them

You can pick your flavor. Fonseca is 19, Brazilian, and hits the ball so hard it sometimes looks rude. He won Basel in the fall, took Buenos Aires on clay, closed 2024 by winning the NextGen Finals, and currently sits around 31 with a career high of 24. The forehand is the obvious thing. Less obvious is how settled he looks on court, like he's already decided he belongs. Brazilian crowds have adopted him the way Argentine crowds adopted Del Potro in 2009. The catch is scheduling. He played too much late last year, arrived at the Australian Open cooked, and lost early. The talent is clearly top-10. The body and the planning need to catch up.

Tien is the other end of the spectrum. Left-handed, 20, born in California to Vietnamese parents. His mom named him Learner because she thought life was about learning, which is maybe the most American story in tennis right now. He made the quarterfinals of the Australian Open in January and climbed to a career high of 21. He's not going to overpower anyone. What he does is absorb pace and stay composed when the match starts to slip away from the guy across the net. Michael Chang is coaching him now, which is almost too on-the-nose, but the style actually fits.

Same goal, two opposite games. If Fonseca's version of winning a slam is hitting harder than anyone can handle, Tien's is waiting for them to miss. Both are real paths. I'd bet Fonseca reaches a final first but Tien wins one first, if that makes any sense. (It might not.)

Jakub Mensik

Mensik is the weirder pick, and maybe the better one. Twenty-year-old Czech with a serve that gets genuinely ugly when he's on, 140+ and barely landing in the box, plus a drop shot he'll pull at 0-30. He won Miami last year in straight sets over Djokovic, denying his idol a 100th career title in the process, and he now has a career high of 12.

What I like is that he's not trying to be anyone in particular. Fonseca has the "next South American superstar" frame. Tien has the Chang comparisons. Mensik is just a tall Czech kid with a hammer and decent hands, and he doesn't seem to care that nobody outside the tour has heard of his coach. On hard courts especially, I'd take him against most of the top 10 on a neutral day.

Arthur Fils

Then there's Fils, who's the comeback angle in this conversation. Twenty-one, French, career high of 14 last spring before a back stress fracture took him out for eight months. A lot of people quietly wrote him off. That was apparently a mistake. Since returning in Montpellier in February he's gone 17-5, reached the Doha final against Alcaraz, made the Miami semis, and just won Barcelona on Sunday by beating Musetti and Rublev back-to-back on clay.

Fils is slightly older than the rest of this group and has the most tour-level wins, which is a meaningful gap at this age. The game is a huge forehand plus a backhand that's better than people realize. He's back to French No. 1, up to 25 in the rankings, and into the Madrid draw as the 21 seed. If his back holds up for a full season, he's probably the most immediately dangerous of the group.

The honest take

None of these four is beating Sinner or Alcaraz in a five-set final this year. Probably not next year either. But one of them will eventually, and the only real question is which one, and on what surface.

Fonseca on clay feels the most likely. Tien on hard, the most achievable. Mensik is a wildcard anywhere his serve is landing. Fils has the most complete profile right now if his back holds up.

For the first time since Sinner and Alcaraz took over the top of the rankings, there's actually a real answer to "who else?" rather than a polite shrug. Four kids under 22, all of whom look like they could win a slam. That's a lot more interesting than where we were a year ago.