'Not a bad serve to copy': Darren Cahill details Jannik Sinner's bold serve makeover

Jannik Sinner's coach, Darren Cahill, has shed light on the significant changes made to elevate the Italian's game over the past year and a half. The World No. 1 has apparently been mimicking the serve of none other than John Isner, the tennis player with the most aces in history, boasting a career total of 14,470.

The three-time Grand Slam champion has become a dominant force on hardcourts and now possesses one of the most effective serves on Tour. In fact, he leads the Tour in service games won over the last 52 weeks with an impressive 91.2%. He's also ranked 4th in first serve won and 1st in second serve won.

Sinner is currently competing at the Halle Open, preparing for Wimbledon, where the serve carries immense weight. On grass, long rallies are rare, making it vital to maintain a consistent and powerful serve throughout the match.

In a recent episode of the "Served with Roddick" podcast, Australian coach Darren Cahill discussed the adjustments made to improve Sinner's serve. "We said it was a three-step plan with his serve because his serve was very side on and there was no shoulder rotation at all, so he started with the action with the shoulders and then we moved it to the step up."

Cahill explained the timing: "The reason why we went to the step up right before Wimbledon was in one year is he took that bad loss, he thought it was a bad loss, it was Daniel Altmaier played incredibly well at Roland Garros in the second round. He goes 'we're going to do it now.' So within a day, we went to the courts and Roland Garros. He goes, right, 'what do I need to do?' We copied John Isner a little bit at the start. Not a bad serve to copy."

The World No. 1 has started the grass-court swing in strong form, with a 7-5, 6-3 victory over Yannik Hanfmann. In the Round of 16, he's set to face Alexander Bublik this Wednesday, whom he defeated just weeks ago in the Roland Garros quarterfinals.