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After the Brazilian became the 10th-youngest title-winner in the ATP Tour era with his triumph at the IEB+ Argentina Open in Buenos Aires, Alcaraz and Zverev were asked for their thoughts on the powerful 18 year-old.

“I was watching the match. I think he played a great match, his first ATP Final,” Alcaraz said. “It's not easy to face an ATP Final, and playing against Francisco Cerundolo in his hometown, I know it wasn't easy. 

"I think the level he played, it was insane. I was just really happy about him playing and getting his first ATP title.

“His potential is huge. His level is really, really high. I saw a stat that in this part of the year last year he was No. 660, and now he is No. 68. So, I'm pretty sure during the year he's going to get higher.”

Alcaraz knows how it feels to have a meteoric rise as a teenager. Aged 19 in 2022, he became the youngest No. 1 in ATP Rankings history after his triumph at that year’s US Open. 

While he was reluctant to commit to any bold predictions about Fonseca’s future, the Spaniard acknowledged he was excited at the prospect of a first meeting with the young talent.

“Potential No. 1? I don't know. I think nobody knows that,” Alcaraz said. “I can say let's see in the future, but he has potential, he has the level to get there or to fight for great things. So, I'm excited to see him in real life in a match. I'm excited to see if I'm going to play against him soon.”

Fonseca will this week compete at his home tournament, the Rio Open. When asked about the Brazilian's chances at his home tournament, one of the players out to stop him echoed the thoughts of Alcaraz.

“Actually, I had a similar run through like him,” Zverev said. “I mean, similar ages, everything, breaking through Top 100, similar age, reaching my first tour-level final at a similar age and all that. So kind of a similar run through.

“I think the most important is, yes, he has talent. Of course, he has talent. Otherwise, he wouldn't have the results that he's having. You wouldn't beat the players that he's beating and all of that. 

"But I think the number one, most important thing is, I think everybody around him needs to calm him down. I talked to him. I know him quite well, and he seems like a nice guy. He seems like a very nice kid, and he seems like a very down to earth person.”

Zverev, who reached his third Grand Slam championship match at January’s Australian Open, believes remaining focused on building upwards step by step is key for young players such as Fonseca to continue their development.

“I think the most important thing is to realise, ‘Okay, these are just the first stages, and we all need to settle down’,” he said. “It doesn't mean that, after tomorrow, I'm going to be World No. 1. I'm going to win 25 Grand Slams and be the best player of all time. 

"There's still a long process to that. There's still a long process to becoming a Top 20 player, becoming a Top 10 player, competing for Master titles, competing for Grand Slams.

“It's all the process, and he's doing all the right things. I think he's playing tennis the right way. Also, I think he has good people around him. I think time will tell, but I think he has everything to be a great player.”