Jannik Sinner has changed his medical setup as he works toward a return to tennis in 2027, and Darren Cahill’s latest visit to Monte Carlo has raised new questions about their coaching partnership. The Italian has not competed since winning Wimbledon on July 12, and his recurring right-knee problem has now forced him to reconsider both his recovery plan and the timeline for his comeback.

According to reports from Italy, Sinner will no longer rely on J Medical in Turin for his rehabilitation. He has turned to orthopedic specialist Herbert Schoenhuber, with Alberto Zangrillo, clinical director at San Raffaele Hospital, also involved in his care. Italian media have linked the problem to inflammation of the iliotibial band in his right knee, although Sinner’s team has not publicly released a detailed diagnosis.

The change follows another setback after Sinner tried to resume training ahead of the Asian swing. His treatment has focused on rest and physiotherapy, and the next step could involve limited on-court tests to assess how his knee responds to tennis-specific movements. These sessions would help his team evaluate his progress, not confirm that he is ready to compete.

The Australian Open in January remains the main target for his return to official competition. A possible appearance at the Six Kings Slam exhibition from December 27 to 30 has also been discussed, but his participation remains uncertain. His recovery will determine whether he can test himself before the new season or needs to wait until Melbourne.

Cahill’s presence in Monte Carlo has added another layer to the situation. According to La Gazzetta dello Sport, the Australian coach travelled to meet Sinner as questions continued over their partnership. Cahill had been expected to leave at the end of 2026, when his contract expires, but Sinner’s extended absence has reportedly opened the door to an extension.

One possibility is for Cahill to stay through the Australian Open, with a longer arrangement until Roland Garros in June also under discussion. A report from TennisUpToDate, citing La Gazzetta dello Sport, described the latter scenario as a way for Cahill to “make up for” the months Sinner has lost to injury. Neither option has been confirmed.

Cahill and fellow coach Simone Vagnozzi have helped Sinner win five Grand Slam titles and reach world No. 1. Keeping Cahill through the early part of 2027 would give the pair more time to manage the comeback before a potential coaching transition. For now, however, the immediate priority is Sinner’s recovery, and the Monte Carlo meeting does not establish that an extension has been agreed.

Sinner’s Injury Could Also Cost Him Millions

Sinner’s absence has consequences beyond missed matches. According to Express UK, he risks losing a reported £3.3 million ATP bonus after missing three Masters 1000 tournaments this season. The bonus is linked to results across designated Masters events, so his strong performances earlier in the year may not be enough to preserve his eligibility.

The financial hit comes after Sinner missed the US Open and several other tournaments during the second half of the season. He had won Wimbledon and built a strong record before his knee problem forced him to stop. His absence has also allowed Alexander Zverev to overtake him in the ATP rankings, adding a competitive consequence to the lost prize-money opportunities.

Zverev, meanwhile, could receive a reported £1.88 million bonus for finishing as runner-up in the relevant standings. That payout is not yet guaranteed, as the final order depends on results at the Paris Masters and how Zverev fares relative to Arthur Fils. The figures reported by Express UK therefore describe potential outcomes rather than confirmed payments.

The bonus is separate from the prize money Sinner missed by withdrawing from tournaments. He also lost the chance to defend his titles at the Paris Masters and ATP Finals, where he had collected significant earnings in 2025. Italian financial reporting has put his potential lost tournament income and bonuses considerably higher when those missed opportunities are included, although estimates vary by source.

Sinner’s injury has therefore affected his season in several ways: he has lost opportunities to compete, risks a substantial ATP bonus, and has seen his position at the top of the rankings come under pressure. Still, the immediate decision is about his health. His medical team must establish how his knee responds to a gradual return to training before he can set a reliable comeback date, and Cahill’s future may become clearer as those plans take shape.