Jannik Sinner has been dismantling opponents with a serve so dominant that even his fellow professionals can barely believe what they're watching, and now we know why. In a candid episode of their podcast The Player's Box, WTA stars Jessica Pegula and Madison Keys revealed that Sinner's remarkable service improvement traces directly back to a deliberate study of big-serving American John Isner.
According to Keys, coach Darren Cahill issued Sinner a straightforward challenge early in their partnership: identify someone with an elite serve and simply learn from them. Sinner reportedly chose Isner, absorbed what he needed, and then went to work. The results have been nothing short of extraordinary.
Pegula was particularly vocal in her admiration, calling Sinner's serve a "joke" in the most complimentary sense and singling out his wide delivery on the ad side as genuinely baffling. She described a feeling shared by many viewers, the sense that there is no way he would attempt that low-percentage ace again, only to watch it land perfectly. "I don't understand," she said, summing up the collective bewilderment.
The statistics back up every word. Over the past 52 weeks, Sinner's service rating of 302.4 ranks second on the ATP Tour behind only Reilly Opelka. He also leads the entire tour in service games won at 92.9% and first-serve points won at a staggering 80.9%.
Those numbers have fuelled a stunning 2026 season: five Masters 1000 titles, a Wimbledon title defence, and a 44-3 win-loss record. He has already secured his spot at the Nitto ATP Finals and leads the ATP Live Race by over 1,400 points.
TennisDraw users backing Sinner deep into every bracket this year have had very little reason to regret it.
