The aura around Jannik Sinner has shifted. No longer the intriguing newcomer, he’s a Grand Slam champion, a former world number one and a figurehead of a new era in men’s tennis. His recent struggles – a semi-final exit at the Australian Open and a subsequent defeat in the quarter-finals of the ATP 500 in Doha – aren’t simply about wins, and losses. They signal a deeper instability, a dip in form that Sinner himself acknowledges.
The concern isn’t merely the defeats themselves, but the manner in which they’ve occurred. Reports suggest Sinner appears heavier on court, less precise, and lacking the explosive energy that defined his dominant performances over the past two seasons. This downturn in form raises a critical question: what’s happening with Jannik Sinner?
Physical Demands and Team Fluctuations
Sinner’s rise coincided with a deliberate focus on physical conditioning, recognizing the need to withstand grueling five-set matches, particularly in his burgeoning rivalry with Carlos Alcaraz. The Italian demonstrably increased his muscle mass and endurance, transforming from a slender prospect into a physically imposing competitor. However, this transformation hasn’t been without its challenges.
A period of instability within his support team has been evident. Following a positive test for closterbol in Indian Wells in 2014, Sinner parted ways with physical trainer Umberto Ferrara and physiotherapist Giacomo Naldi. Marco Panichi and Ulises Badio later joined the team, but departed before Wimbledon 2025, with Ferrara returning before the US Open. These frequent changes created disruption in his preparation process. At the 2026 Australian Open, Sinner experienced heat cramps in the third round, and appeared fatigued in the semi-final loss to Novak Djokovic – a match he had previously often dominated. That defeat, coming against a long-time rival, undoubtedly had a psychological impact.
Despite acknowledging the challenges, Sinner insisted he felt “fine” after his defeat in Doha, dismissing suggestions of fatigue. However, elite tennis operates on margins, where even a slight decrease in resistance or slower movement can be decisive.
The Pressure of the Alcaraz Rivalry
While Sinner’s form has faltered, Carlos Alcaraz has continued to ascend, underscored by his victory at the Australian Open – a tournament Sinner had won in the previous two years. Losing the world number one ranking to Alcaraz has added another layer of pressure. This rivalry extends beyond rankings; it’s a battle for the future of men’s tennis, with each title won by Alcaraz directly impacting Sinner’s position.
Throughout 2025, Sinner lost to Alcaraz in several high-profile finals, including Rome, Roland Garros, Cincinnati, and the US Open. While he secured a victory at Wimbledon, the losing streak left a mark on his confidence. Responding to this challenge, Sinner has sought to diversify his game, aiming to become “more unpredictable” by improving his net play, serve, and attacking options. However, venturing outside his comfort zone carries inherent risks, and performance fluctuations are to be expected during this experimental phase.
Sinner admitted to adding “some new things,” but acknowledged it hasn’t always been seamless. His defeat against Jakub Mensik in Doha highlighted the ineffectiveness of these adjustments. Changing the fundamental structure of a player’s game requires time and patience, a process that is currently unfolding for Sinner.
The composition of Sinner’s coaching staff is similarly under scrutiny, with rumors linking Carlos Moyá or Juan Carlos Ferrero to his team. Currently, Darren Cahill continues to work with him, Simone Vagnozzi remains as head coach, and agent Alex Vittur plays a strategic role. While some Italian experts believe a change could inject fresh energy, altering the team based on public pressure isn’t necessarily the solution.
Sinner is now in a different position than he was a few years ago. He’s no longer an emerging player aiming to surprise, but a champion tasked with defending his position. Two consecutive losses haven’t fundamentally changed him, but they serve as a reminder that maintaining peak performance is often more demanding than achieving it.
For a player of Sinner’s stature, any crisis isn’t about short-term results, but about his reaction. If he can restore the balance between his physical condition, tactical approach, and mental fortitude, the race with Alcaraz will be a long and compelling one. Otherwise, the gap between them will likely widen.
Elite tennis waits for no one. The question of “What’s wrong with Sinner?” will only be fully answered by his future triumphs, not by reassuring statements following each defeat.
What comes next for Sinner will be closely watched as he attempts to regain his form and challenge for major titles. His ability to adapt, refine his game, and maintain his mental resilience will be crucial in the coming months.
What are your thoughts on Sinner’s recent struggles? Share your opinions in the comments below.
