Greg Rusedski reveals when Joao Fonseca could emerge as a real threat at the top of tennis

Fonseca has had a solid 2025 season, picking up titles in Buenos Aires and Basel and moving up to world number 24. However, the 19-year-old has yet to break into the very top of the sport, with players like Sinner and Alcaraz continuing to set the pace.

Despite his clear talent, former British number one Greg Rusedski isn’t convinced Fonseca is ready to make that jump just yet.

Fonseca made an immediate impression at the start of 2025, beating ninth seed Andrey Rublev in straight sets before falling to Lorenzo Sonego in five sets later on. It was an early sign of his ability but also showed there’s still work to do before reaching the next level.

The Brazilian has looked impressive at times since then. But according to Rusedski, it’s still early days for him in terms of development:

“He is still young and there is time but he is still too green, as I like to call it. There is still a long developmental period of at least two years before we see what he is made of,” Rusedski added.

Sinner and Alcaraz were both at different stages by Fonseca’s age and were further along in their development – something Rusedski was quick to highlight.

What is the right Grand Slam target for Joao Fonseca next season?

Fonseca has enjoyed his best Grand Slam runs at Roland Garros and Wimbledon, making the third round at both tournaments in 2025.

By next season, though, he should be looking beyond those early-round exits.

The Brazilian’s raw ability is clear to see and it won’t be long before his results start to reflect that. It’s really just a matter of gaining more experience on the big stage.

Fonseca could realistically set his sights on reaching a Grand Slam quarter-final in 2026, with a semi-final appearance as an ambitious but attainable goal.