There’s one 18-year-old Brazilian kid on the ATP tour who’s become a huge sensation in the last one year. Especially after turning pro and wreaking havoc on the court wherever he goes, attracting massive fan waves. So much so that it feels akin to a “Federer-like frenzy.” Back in December, he won the Next-Gen ATP Finals title Jeddah and hasn’t looked back. Yes, there have been obstacles in meeting expectations, but the teenager is still being touted as the one who might challenge the undisputed reign of Carlos Alcaraz and Jannik Sinner in men’s tennis going forward. What Djokovic was to Federer and Nadal’s intense rivalry, this youngster is expected to take up the exact role. But can he?

Well, that’s the one burning question revolving around Joao Fonseca. After becoming the ATP Finals champion last December, he simply declared, “My dream is to become No. 1.” The teenager began his professional journey at this year’s Australian Open. And he put up a great performance, too, giving promising signs. After dismantling a top-ranked opponent like Andrey Rublev, however, his journey couldn’t extend further. He lost in the second round to Italy’s Lorenzo Sonego in a hard-fought five-setter. He did win his first-ever mainstream ATP title at the Argentina Open—but that was it. For the last few months, he’s been struggling to meet the hype behind him.

However, a former American ATP icon believes that Fonseca has got that spark to rise to the occasion. So much so that he may also challenge Carlos Alcaraz and Jannik Sinner’s ongoing supremacy. During an episode of the Nothing Major podcast, a fan posed this question: “Do you guys ever see Fonseca catching Carlos or Sinner in his career? And how long would that take?” Making an honest admission, ex-pro John Isner answered, “I know we pump up Fonseca a lot. But for the sake of the health of our sport, and I actually do believe this, I’m gonna say yes.”

Elaborating on his take, he added, “I think he can catch up to these guys and get to the conversation. And I am not saying that next year or year after, I think in four-five years he can be in the conversation where he is one of the top four favorites to win each slam he enters.” However, he did point out that the Brazilian may not improve as much as Alcaraz and Sinner. “So I’m gonna say yes, but not to the level they are at. Like, I think he can get to that level where he’s expected to make the final four of these Grand Slams. That’s my take.”

Interrupting him, compatriot Sam Querrey then asked, “So not to their level?” To this, Isner simply replied, “I mean, not quite. But he’s gonna be up there, right? I mean, it’s hard to say he’s going to be as good as Sinner right now in four years.” Concluding his point, Isner said, “He’s not going to win; he’s not going to roll off four slams in two years but I think he can win one or two in the span of two or three years.”

Apparently, he’s not the only one who thinks Fonseca can dismantle the Spaniard and the Italian’s unparalleled domination. A former Aussie pro has got a similar perspective too.

Ex-Australian player backs Joao Fonseca to take on Jannik Sinner and Carlos Alcaraz

After the epic French Open final at Court Philippe-Chatrier in Paris, Alcaraz and Sinner have proved the extent they can go to in order to display tennis of the highest order. What a remarkable cliffhanger that 5-hour-29-minute battle was! Not to mention their second straight face-off in a slam final at Wimbledon. Both of them showed top-notch quality of shots, to say the least.

Former Aussie pro Luke Saville thinks the World No.1 and No.2 are shaping up the racket sport like never before. “I feel like they’re clearly the two best in the men’s game right now,” he said, as reported by the Australian Open’s website on July 18.

But then he also brought the 18-year-old Brazilian into focus. “I think everyone’s looking at (Joao) Fonseca to be the next challenger to those two,” stressed Saville. Still, he admitted, “It’s Carlos and Jannik and then there’s daylight, at the moment.”

Fonseca has yet to prove himself on the biggest stages. Especially during his slam campaigns. While he’s failed to leave a huge impact in 2025 in Melbourne, Paris, and Wimbledon (with early round exits), he can still do so at the US Open. Do you think the World No.48 will emerge as the biggest surprise at the Flushing Meadows? Let us know in the comments below.