Jannik Sinner is back in training following his defeat to Carlos Alcaraz at the US Open.
The four-time major champion missed out on a fifth in New York, as Sinner lost to Alcaraz in the US Open final.
Sinner was outclassed by his rival on Arthur Ashe Stadium, producing a well-below-par serving performance in the final.
Photo by Clive Brunskill/Getty Images
Many highlighted the shot as a weakness in his game after the match, with Italian tennis legend Paolo Bertolucci claiming Sinner must improve his serve if he wants to beat Alcaraz in the future.
Since then, footage has been leaked of Sinner in training, which suggests he may have listened to his countryman.
Ahead of his trip to China for the beginning of the Asian swing, Sinner has been training in Monte-Carlo.
The Italian was seen focusing on his serve in training, with one particular clip showing Sinner practising the shot without a racket in hand.
At the Monte-Carlo Country Club, Jannik Sinner is working on his serve — this time without a racquet.
A key element that let him down at the US Open, especially in the final.
Sharpening every detail as he prepares for the season’s closing stretch. 🦊🎾
— The Sinner Times (@sinnertimes) September 16, 2025
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Such emphasis on the serve can only be good news for fans of the world number two, who raised their concerns over the shot during the US Open.
Sinner’s serve was far from its best at Flushing Meadows, but was particularly poor in the final, where he trailed Alcaraz in every meaningful statistic.
PlayerAcesDouble faults1st Serve %Win % on 1st ServeWin % on 2nd ServeCarlos Alcaraz10061%83%57%Jannik Sinner2448%69%52%Serving stats from Carlos Alcaraz vs Jannik Sinner
Making just two aces to Alcaraz’s ten, Sinner struggled to take control of his service games, which led to him being broken on five occasions.
Photo by HENRY NICHOLLS/AFP via Getty Images
Working on his serve in training, Sinner has followed in the footsteps of his rival, who did the same thing earlier this year.
Carlos Alcaraz fixed his serve during the 2024/2025 off-season
Ahead of the 2025 season, Alcaraz made a significant change to his serve, looking to become more efficient.
Alcaraz admitted it was taking some time for the adjustments to feel natural before the Australian Open began.
“Right now, I am still thinking about it. I am still reminding myself how I have to do it,” he said.
Photo by Andy Cheung/Getty Images
“Every day is getting better and better and feeling better and better with it. We knew I had to change something in the serve to be better at it.”
The improvements weren’t evident right away, as Alcaraz lost to Novak Djokovic in the Australian Open quarterfinals, hitting five double faults in that match, but he was right up to speed by the time the US Open came around.
Producing arguably the most clinical serving performance of his tennis career, Alcaraz won his sixth Grand Slam title in style.
Alcaraz and Sinner have both made/are making changes to their serves in 2025, but where do they rank among the ATP Tour’s best over the past 12 months?
Carlos Alcaraz and Jannik Sinner both rank in the top ten for ATP Tour Serve Rating
‘Serve Rating’ is a composite measure that takes several different factors into account, assessing a player’s serving capabilities.
First serve %Win % on first serveWin % on second serveWin % of service gamesAverage aces per matchAverage double faults per match
The world number one and two both rank inside the top ten for Serve Rating, but which of the pair has been better according to the statistics?
RankNameServe Rating1st Serve %Win % on 1st ServeWin % on 2nd ServeWin % of Service gamesAvg aces/matchAvg double faults/match1Giovanni Mpetshi Perricard297.364.579.253.789.614.94.62Jannik Sinner296.360.678.959.692.06.71.53Taylor Fritz296.263.979.454.389.311.11.84Alexander Zverev295.271.275.254.788.37.92.15Novak Djokovic294.066.576.855.988.88.02.06Matteo Berrettini292.268.875.852.286.610.21.47Reilly Opelka291.961.478.951.488.316.14.28Ben Shelton291.765.175.855.788.79.43.09Carlos Alcaraz287.464.174.757.388.05.92.610Brandon Nakashima286.366.074.553.484.98/71.2ATP Tour Serve Ratings over the last 12 months
Interestingly, Sinner sits second in the rankings, with Alcaraz currently down in ninth.
Whether things change in the future remains to be seen, but it will certainly be something to look out for.
Sinner’s new-look serve will be seen in action for the first time at the China Open, which begins on Thursday, September 25, while Alcaraz returns to the court at the Laver Cup, which gets underway on Friday, September 19.