Carlos Alcaraz, the 21-year-old Spanish tennis sensation, has already carved out a legacy that most players can only dream of. With four Grand Slam titles, including the 2022 US Open, 2023 and 2024 Wimbledon Championships, and 2024 French Open, he’s the youngest man to win majors on hard, grass, and clay. Yet, despite his meteoric rise, former American ATP star John Isner believes Alcaraz is nowhere near his peak. In a recent discussion, Isner made a striking prediction: Alcaraz’s best tennis is still years away, potentially five years from now, when he’ll be 26. “I don’t think this is what we are going to see for the next five to eight years,” Isner declared, pointing to the Spaniard’s youthful inconsistencies as a sign of untapped potential.
Alcaraz’s 2025 season has been a thrilling ride, blending jaw-dropping highs with occasional stumbles. His Monte Carlo Masters title, where he outlasted Lorenzo Musetti in a gripping final, and his commanding start at the Barcelona Open, extending his 12-match winning streak there, showcase his dominance. Yet, losses to players like Jiri Lehecka in Doha and David Goffin in Miami reveal the growing pains of a 21-year-old juggling immense expectations. Isner, a former world No. 8 and Miami Open champion, sees these ups and downs as part of Alcaraz’s evolution. “It is easy to forget that he is still only 21 years old,” he said. “He hasn’t even reached his peak. He is still so young and has so much maturing to do even though he is so ridiculously good.”
Isner’s confidence stems from Alcaraz’s raw talent and versatility. Coached by Juan Carlos Ferrero, whom Alcaraz calls a “second father,” and new assistant Samuel López, the Spaniard wields a game that’s equal parts power and finesse. His blistering forehand, deceptive drop shots, and relentless court coverage make him a nightmare for opponents. At Barcelona, where he dispatched qualifier Ethan Quinn 6-3, 6-2, fans roared as he unleashed a pinpoint lob to seal a break. But Isner argues it’s Alcaraz’s mental growth that will elevate him further. “I think he will shore that up and become more consistent,” he predicted, suggesting that by his mid-20s, Alcaraz could iron out the lapses that cost him in tight matches like Doha, where he squandered a 4-2 lead in the deciding set.
The prediction isn’t without context. Alcaraz’s 2024 season, while historic, had its hiccups—an early US Open exit to Botic van de Zandschulp, breathing issues at the ATP Finals, and a group-stage loss to Casper Ruud. These moments, Isner believes, are mere stepping stones. “This year and maybe next year he might have some inconsistent results and some losses which make you scratch your head a bit,” he noted, citing the Lehecka defeat as an example. Yet, Alcaraz’s ability to bounce back—winning Indian Wells for the third straight year and battling through illness to honor Rafael Nadal’s Davis Cup farewell—shows a resilience that Isner admires.
The tennis world is watching a generational shift, with Alcaraz and Jannik Sinner leading the charge as Novak Djokovic ages and Nadal steps back. Alcaraz’s rivalry with Sinner, who holds the No. 1 ranking, promises epic battles, but Isner’s focus is on Alcaraz’s individual trajectory. At 26, with physical maturity and refined decision-making, he could dominate like few before him. “It is crazy to think that he has not even come close to reaching his highest level as a tennis player,” Isner marveled, a sentiment echoed by peers like Ben Shelton, who called Alcaraz “capable of hitting every shot imaginable.”
For now, Alcaraz remains focused on the present, chasing a third Barcelona title and eyeing the Australian Open to complete a career Grand Slam. His ambition is clear, but Isner’s words paint a bigger picture—a future where Alcaraz doesn’t just win but redefines greatness. As the clay season unfolds, every match is a step toward that peak, and if Isner’s right, the tennis world hasn’t seen anything yet.