Player Features
Cahill’s deep dive into ‘Competition animal’ Sinner
Australian coach discusses the key factors behind his charge’s rise to No. 1
August 11, 2025
Peter Staples/ATP Tour
Darren Cahill (right) has worked with Jannik Sinner since July 2022. (File photo)
By ATP Staff
A No. 1 in the PIF ATP Rankings is not built in a day.
Jannik Sinner has now been entrenched at the top of tennis’ mountain for 14 consecutive months. The Italian’s success has been the product of a relentless work ethic and desire to improve that has been facilitated by his coaches, Darren Cahill and Simone Vagnozzi.
Cahill and Vagnozzi joined Sinner’s team within six months of each other in early 2022. Since then the Italian has lifted four Grand Slam titles, the Nitto ATP Finals crown and four ATP Masters 1000 trophies. The greater the stage, the more explosive Sinner seems to become when he steps on court.
“That’s why we are so proud as coaches, because all that work you’ve been doing for the past three years eventually shows up in a big match, at a big tournament, for him to be able to get through and win that match,” Cahill told ATP Media at the Cincinnati Open. “So it’s not just four or five days when you can make those big changes. It’s the combination of a year or two of just pushing him day to day and making sure we continue to work on those things.”
Watch full interview: Darren Cahill on ‘Competition animal’ Sinner:
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Cahill specifies one clear area he identified as a priority when he began working with Sinner in July 2022.
“One thing I did say is, ’The serve needs to improve. You’re six foot four and you’re a strong lad’,” recalls the Australian. “’You need to be able to get more miles per hour on that first serve, better direction on that first serve. Then not only do you start winning some free points from your first serve, but also your Plus One becomes much more effective. If people can neutralise your serve, you have to work much harder for your points.’
“Then his questions came, one after the other… It’s typical of him. He wants to compete. He’s a competition animal. We’re seeing an incredible level of tennis at the moment, with Carlos [Alcaraz] and Jannik. If you look at their body of work over the past couple of years, they’ve separated themselves from the field. Now it’s up to the field to chase.”
Sinner will face Gabriel Diallo on Monday in the fourth round in Cincinnati. The 23-year-old Italian will enter the match with a 27-3 record for the season, according to the Infosys ATP Win/Loss Index.