WATCH: 'You're f***ing sitting': Jannik Sinner gets unusually angry with his team

Jannik Sinner is known for being one of the coolest competitors on the ATP Tour, but he became uncharacteristically cranky with his team at the 2025 Paris Masters.

Sinner shares a very close relationship with co-coaches Darren Cahill and Simone Vagnozzi, who have played a pivotal role in his rise over the past few years. Earlier this year, Cahill revealed he would retire from coaching at the end of this season.

However, Cahill's future has become uncertain. Rumors have circulated about him staying with Sinner in some capacity, possibly traveling less but appearing at some of the most significant tournaments.

It is challenging to think of any previous instances of Sinner becoming agitated with his team. The four-time Grand Slam champion rarely shows any emotion and usually ruthlessly takes care of business.

That efficiency was shown in the Paris Masters quarterfinal against Ben Shelton. Sinner defeated the American for the seventh consecutive time, and it reiterated how much work he must do to compete with Sinner and Carlos Alcaraz.

The Italian broke Shelton's massive serve four times. After one of those occasions, Sinner's team celebrated his effort, but did not get off their seats, which left the world No. 2 feeling irritated by what he perceived as a lack of effort.

When the changeover finished, Sinner briefly went to his towel, which was placed right beside where Cahill, Vagnozzi, and the other team members were. He said, "I make a break, and you're f***ing sitting," before walking away.

Although Sinner did not raise his voice or make any significant scene, it was still a highly unexpected moment. He would generally be regarded as one of the least likely players to swear at anyone on court.

The moment does not indicate any rift between Sinner and his team members. His brief moment of frustration was immediately greeted by encouragement from them, showing they understood the need to bring more energy.

Sinner's annoyance could be a good thing. He might be coming out of his shell in a way that allows him to communicate what he expects more efficiently, which can actually make Vagnozzi and Cahill's jobs easier.

Before the Paris Masters began, Sinner said there was no chance of him finishing as the year-end No. 1, and the possibility of him reaching that spot again at all before 2025 ends also seemed minute.

Carlos Alcaraz's shocking round-of-32 defeat to Cameron Norrie changed everything. The Spaniard had reached the final of every tournament he entered since the 2025 Monte-Carlo Masters before Norrie bested him in the French capital.

Sinner followed his triumph over Ben Shelton with a 6-0, 6-1 win over a physically hampered Alexander Zverev. The German could not recover from a lengthy and grueling quarterfinal against Daniil Medvedev on Friday night.

If Sinner defeats Felix Auger-Aliassime in the final, he will return to No. 1 when the new rankings are released on Monday. However, Alcaraz remains the favorite to finish as the year-end No. 1 because Sinner will defend the points he won from winning the 2024 ATP Finals.