'Just unbelievable' - Joao Fonseca defeats Francisco Cerundolo; becomes youngest player to win ATP title

Joao Fonseca's spectacular rise reached new heights on Sunday when he won his first tour-level victory at the IEB+ Argentina Open in Buenos Aires. By defeating the fifth seed Francisco Cerundolo 6-4, 7-6(1), the 18-year-old Brazilian put on an incredible display and became the youngest South American to win a title in the history of the ATP Tour (since 1990). 

In front of a boisterous crowd in the capital, Fonseca, who was playing in his first tour-level final, regrouped spectacularly to sink a fourth Argentine of the week after serving for the match twice without success. A year ago Fonseca was ranked No. 648 in the PIF ATP Rankings. In the 52 weeks since his career has taken off. Having upset Andrey Rublev as a qualifier at the Australian Open, won an ATP Challenger Tour championship, and now taken home his first ATP Tour prize, the teenager has started the 2025 season on a strong note.

"Unbelievable week, even in Argentina some Brazilians are cheering for me," an emotional Joao Fonseca said. "That's just amazing. Every Brazilian, everyone from their country wants this support from your country. For me, this [moment] that I'm living is just unbelievable", he said in an interview after the match.

In his quarterfinal match-up with Mariano Navone, Fonseca was about to lose, but he showed tenacity to salvage two match points and pull off an incredible comeback win. Fonseca might have been worn out after winning three of his four matches in deciding sets before the final. However, the teenager found an extra boost of energy to push over Cerundolo in a blazing second-set tie-break.

Tenth youngest champion in ATP Tour

He is the first 2006-born winner and the tenth youngest champion in ATP history. Following a hitting session in 2023, world number one Jannik Sinner convinced Fonseca to become a professional, making him the tournament's second-youngest champion following Sinner's victory in 2019. He will move up to 68th place in the global rankings before heading to the Rio Open, his home tournament, which starts on Monday.