“We want him playing his best tennis at 28, 29, 30”: Darren Cahill outlines ambitious long-term plan for Jannik Sinner’s rise

The victory of Jannik Sinner over Carlos Alcaraz gave him back-to-back titles at the ATP Finals, in addition to a sweet way to end the season, after ceding the World No. 1 ranking to his rival a few days earlier. Sinner's coach, Darren Cahill, referred to the keys behind Sinner's victory and his extraordinary level in the tournament, though he warns that the Italian is far from having reached his peak.

Darren Cahill has become an increasingly central figure in Jannik Sinner’s evolution. The Australian originally planned to step away from full-time coaching at the end of this season, fter years travelling the ATP and WTA Tours with names such as Simona Halep and Andre Agassi, Cahill intended to retire to spend more time with his family in Australia. But Sinner’s run to the Wimbledon title altered the picture, with both agreeing he would stay for at least one more year.

Cahill’s role has only grown more visible following Sinner’s recent triumph over Carlos Alcaraz in the 2025 ATP Finals. The Italian defeated the World No. 1 by 7–6(4), 7–5, improving their rivalry to 6-10 and closing the season with a 4–2 record in finals against his rival. The match highlighted how much of Sinner’s progress stems from long-term structural planning, rather than short bursts of form. Cahill confirmed that some adjustments are designed with several seasons in mind.

The serve has been a major focus of that development. Cahill explained that their strategy has never been about boosting percentages for the sake of statistics but about increasing the quality of each delivery. “It’s not just a question of first-serve percentage. If we only cared about that, we would tell him to slow down the speed to land more,” Cahill said in press conference, accordint to Super Tennis. “Instead, Jannik has increased the kilometres per hour, he hits closer to the lines, and he gets many more free points.”

While Sinner’s return game already places him among the best on tour, Cahill insists there is still meaningful room for growth. For him, the most exciting aspect is that Sinner’s potential remains far from fully realised. “Although Jannik already returns very well, we feel he still has margins of improvement,” he said. “That’s the interesting and exciting thing about working with someone so strong: there are parts of his game that can still grow a lot. We want him playing his best tennis at 28, 29, 30, so the aim is to set that platform now.”

Cahill has also been vocal about the current conditions on Tour, stressing that a healthy variety of surfaces remains essential for the sport. His assessment of the 2025 ATP Finals court was clear: medium-fast and suited to aggressive players. “I think there is still great variety between surfaces. They’re not all medium-speed courts,” he said. “This one was medium-fast, pretty quick. The difference between Indian Wells and Cincinnati is huge. Indian Wells is very slow. Cincinnati is one of the fastest hard courts on the tour.”

The Australian also addressed an ongoing concern among several players regarding the inconsistency of balls across tournaments. “Maybe the balls could be made a bit quicker,” he suggested. “We’ve talked about it: it would be helpful if tournaments used a more uniform ball, especially between the clay season and the American hard-court swing. It’s a matter of what people want to see: just service winners and fast points, or the exciting spectacle we saw tonight?”

With Sinner now entrenched in the top two and coming off a season in which he and Alcaraz dominated the biggest stages, Cahill’s continuity adds stability during a period of high expectations. Still, the coach will not travel full-time in 2026, something Sinner himself confirmed months ago. The team is expected to divide duties across the season, allowing Cahill to remain involved without the exhaustive schedule that originally led him to consider retirement.

Looking ahead, Sinner’s development on clay remains a major target. The Italian’s game has adapted well across fast, medium, and slow courts, but the team believes the next significant leap could come during the European spring. “I think his game adapts well to all surfaces, slow, fast or medium,” Cahill concluded. “Obviously clay will be a major goal for us next year, to keep improving his tennis on that surface. We’ll continue working on it.”