It’s Vienna. The stakes are high, the courts move quickly, and Jannik Sinner is just one victory away from winning another championship. However, he is thinking about more than just forehands and tactics as he prepares to play Alexander Zverev in Sunday’s Vienna Open final. His coach and mentor, Darren Cahill, is getting ready to retire from full-time coaching after almost three years of working together. But what happens when the man who shaped his career steps away entirely?

Cahill has coached legends like Andre Agassi, Simona Halep, and Lleyton Hewitt. However, with Sinner, things have been different. Since July 2022, he’s shaped not just a player but a person, grounding Sinner’s rise with balance. Recently, a post shared by Jannik Files on X captured Sinner’s heartfelt words: “Darren has given me a lot and I’m grateful for him. He’s not just a coach to me, much more. But we have to understand that he’s 60, so we’ll see. Vagnozzi and I haven’t discussed about the 2nd coach, he needs free time so we’ll talk and decide calmly.”

Earlier this year, Cahill announced that 2025 would be his final year coaching on the ATP Tour. At 60, it seems necessary to take a break because of the toll that decades of travel and constant demands have taken. However, there’s a chance he might change his mind. Il Corriere della Sera claims that Cahill might continue to be a part of Team Sinner in 2026, albeit in a less significant role. Alongside primary coach Simone Vagnozzi, he would continue to coach Sinner, but make fewer trips while still attending important tournaments.

Jannik Sinner has flourished under Cahill and Simone Vagnozzi, reaching deep finals in almost every major he has entered, and winning all four of his Grand Slams under their tutelage. But if Sinner has his way, the collaboration is set to continue: ““We haven’t talked yet, to be honest. We said we are going to finish the year, and then we might ask him for a long chat, trying to convince him… We aim for something very positive [for him to stay], and I will need a lot of hope for that.”

Sinner’s talent and temperament have been demonstrated during this campaign, which Cahill subtly reaffirmed. “The last week[s] were a great confidence boost and for me, most importantly, that the mental aspect is in the right way, in the right spot,” Jannik Sinner said recently. “I’m very happy and grateful for that. I feel good at the moment.” But that mental steadiness will be tested soon if he faces the tough decision of finding who joins Vagnozzi next.

Even with such a successful season behind him, Sinner’s focus remains on respect. “The results have been amazing, so I will try to make it happen for my own well-being… he’s been important because of the effort he puts in and the way he always puts me first,” Jannik Sinner said. He believes that being a champion is about the people who support, believe in, and encourage you to reach your full potential, not just about winning awards.

Jannik Sinner knows when to pause

World No. 2 Jannik Sinner has had a fantastic 2025, winning the Australian Open and Wimbledon, and he plans to continue that success in Vienna, Paris, and the ATP Finals in Turin. But big plans need careful planning. Sinner recently announced that he would put his preparations for defending his Australian Open title over the Paris and Davis Cup Finals in Bologna from November 18–23.

He explained that even a single extra week of focused work can change the start of a season. Protecting his time, his body, and the right voices around him, including longtime coach Darren Cahill, is central to his strategy, especially with ambitions to push for World No. 1 and another strong run at the majors.

This week in Vienna, Sinner will face Alexander Zverev in their first meeting since the Australian Open final, where Sinner claimed a straight-sets victory. The Italian, a 2021 Vienna champion, is chasing his fourth title of the season and hopes to narrow the gap on Carlos Alcaraz, who isn’t competing this week.

Sinner has made the most of his games and performances, referring to 2025 as “an extraordinary season,” despite missing three months of the season from February to May because of a suspension from his 2024 positive doping result. He will end his season following the ATP Finals, skipping the Davis Cup in order to recuperate and prepare for 2026. Because knowing when to quit can be just as effective as knowing when to fight, even for champions.