Andrey Rublev says his behaviour in his third-round French Open loss – where he smashed a racquet on court and on his knee – was the worst it has ever been at a Grand Slam.

Sixth seed Rublev fell to a 7-6 (8-6) 6-2 6-4 defeat against Italy’s world number 35 Matteo Arnaldi.

Rublev showed signs of agitation at the end of the first set – being warned by the umpire after throwing his racquet to the ground.

The Russian shouted at his team after being broken in the second set and bounced his racquet on the clay between Arnaldi serves, drawing ironic cheers from the crowd.

The 26-year-old also hit his knee with his racquet in the third set after continuously kicking his chair.

“Completely disappointed with myself the way I behaved, the way I performed, and I don’t remember behaving worse on a slam ever,” Rublev said.

“I think it was first time I ever behaved that bad.”

Rublev is a 10-time Grand Slam quarter-finalist but has never gone beyond that stage.

He was defaulted in Dubai for unsportsmanlike conduct three months ago but made a conscious effort to control his on-court demeanour, external on his way to the Madrid Open title in May.

“I feel in some moments it is tough to be kind to myself,” he said.

“Of course if I was able, I’m sure that those moments will never happen.

Arnaldi will face either ninth seed Stefanos Tsitsipas of Greece or China’s Zhang Zhizhen next.

Rublev started well, trading breaks with Arnaldi before narrowly losing out in a tie-break.

His frustrations then started to bubble over as his concentration and performance levels began to drop significantly.

Rublev was also seen flexing his knee after slamming the strings of his racquet on it numerous times as Arnaldi closed in on victory.

Former British number one Annabel Croft described it as “tough to witness”.

“He’s such a fun and charming character off the court. You don’t recognise this character who is so tormented,” she told BBC Radio 5 Sports Extra.

“When you see a guy whacking his leg with such physical anger and venom, that’s not good for us to even witness.

“It’s not about him growing up and maturing, but ultimately, tennis is a sport. It’s not the be all and end all.

“He needs to somehow find some perspective with what he’s trying to do.”

Meanwhile, Jannik Sinner continued his bid for a second straight Grand Slam title with a no-fuss win against Russia’s Pavel Kotov.

The Australian Open winner won 6-4 6-4 6-4 to reach the fourth round.

Sinner, who has never gone beyond the fourth round in Paris, struggled with a hip injury in the build-up to the French Open, withdrawing in Madrid and missing his home tournament in Rome.

The 22-year-old Italian was patient against world number 56 Kotov, relying on a single break in each of the three sets and getting through his own service games without needing to up his level.

He will face France’s Corentin Moutet or Sebastian Ofner of Austria next.

Sinner will become world number one should defending champion Novak Djokovic fail to reach the semi-finals.