Jannik the Sinnera work in progress? It sounds funny, but it’s true. And knowing Sinner, his incredible humility and his desire to turn over every stone in the name of becoming a better tennis player every day, maybe it will be forever.
Case in point: the last two months.
The 24-year-old and his plucky team identified weaknesses in his blistering game after this year’s US Open and immediately set to work to ensure Sinner could deliver more power. Truth be told, Sinner has no choice, given the dire consequences he would suffer if he didn’t continue to add weapons to his ongoing arms race with world #1 Carlos Alcaraz.
(He has world-beating Carlos Alcaraz to thank for his "identified weaknesses", because no one else seemed to be able to push the high-flying Italian to his limits in a season that saw him win two majors, reach the final at all four majors, and close the season on a 31-match indoor hard court heater). 
His ever-vigilant team, led by Darren Cahill and Simone Vagnozzi, identified several chinks in the Italian’s armory and drew up a well-documented plan, approved by Sinner, to introduce better serves and more unpredictable play in the 2025 part of the season.
The results were… emphatic.
“For sure after the US Open we saw some problems, especially with the serve,” Vagnozzi said after Sinner defeated Alcaraz 7-6(4), 7-5 on Sunday in the ATP finals. “We changed the movement. We changed the tempo. He served very well from Shanghai to here. Today in the second set he struggled a little bit.
“We changed a lot of things after the US Open. We’re lucky to have Jannik who is really quick to improve, to understand the changes and everything.”
Vagnozzi was quick to add that the plan hasn’t seen fruition so far – look for more subtle but effective changes in 2026.
“Also we try to do new shots, new tactics as well,” he said. “I won’t tell you what we try to do”, said the Italian smiling. “Of course, our goal in the next season is to be more aggressive than we are now.”
Even Sinner was pleased with his adaptation measures and the ever-humble 24-year-old adds that he still has a way to go.
“(My game) has evolved in a positive way, of course, especially the serve,” he said. “From the back end of the court, it’s been a little more unpredictable. It’s worked well, or at least better. I believe I still have gaps where I can play better at times.”
His coach Darren Cahill, who may or may not be part of the team in 2026 (a different story for another day, stay tuned), says he believes Sinner still has plenty of room for improvement in areas like his return game and his performance on clay.
“In terms of Jannik’s game, I think his game goes well on all surfaces, whether it’s slow, fast or medium,” Cahill said. “Obviously, clay is going to be a big target for us next year, to continue to improve his ground game. We’ll continue to work on that.
“We still feel like, as good as Jannik’s return serve is, he has areas in that part of his game where he can improve. That’s the really interesting and exciting thing about working with someone as good as Jannik, is that there are parts of his game that we still feel can be greatly improved.”
It was reported that this would be Cahill’s last season as Sinner’s coach in January, but by Wimbledon the pair had already started to return notice. There was a bet at Wimbledon and if Sinner won, it was said that he could decide whether or not Cahill would return to the group in 2026.
Asked about it again on Sunday, Cahill deferred, saying “We haven’t spoken yet, so…”
But the legendary Austrian sounds like a man very invested in Sinner’s future when he speaks.
“I think it’s a little bit of what I talked about here a week ago, that we want him to be playing his best tennis when he’s 28, 29, 30 years old. Hopefully we’re setting the plan and the platform for him to be able to do that in a couple of years.”
Sinner seems excited to spend December implementing new facts of his ever-expanding repertoire. He will have to if he wants to keep up with Alcaraz, who has won four of six matches against him this year, and two of three major finals.
“As I always say, December is very important for me as a player and as a team because you bond better because you don’t have the pressure of the tournament, the rush to go from one side to the other.
“It’s very important not only because of the work ethic, but also to bond the whole team better and to understand each other even better.”
