Jannik Sinner is still only 22 but he strolls in with the serene conviction of a grand slam winner who seems far older than he looks. He is also as friendly as he is serious in a mix that suits the fact that Sinner is an Italian who grew up speaking German and now models for Gucci while sometimes being cheered on by a quirky group of fans who dress like carrots and call themselves the Carota Boys. The carrots honour Sinner’s red hair and the fading memory that he once ate the humble vegetable during a match in Vienna.

It makes sense to meet Sinner at Roland Garros for it was here, a year ago, that a surprise defeat changed his erratic mentality and set him on a new path of clarity. Sinner’s uncluttered purpose since then has meant he has beaten Novak Djokovic in three out of their past four matches, lift the Davis Cup for Italy, win the Australian Open in January and rise to No 2 in the world.

But we start with the painful loss that unfolded over five hours and 26 minutes against the unheralded Daniel Altmaier in the second round of last year’s French Open. Altmaier exposed psychological flaws that shocked Sinner into the changes that have transformed him.

“I’m always trying to learn from my losses and that was a tough one,” he says. “My mindset was not great and I promised myself this attitude won’t happen again. It was time to try my best with a smile. There is pressure, obviously, but pressure is a privilege.”

Sinner shrugs wryly as he recalls a tumultuous match he led by two sets to one before being unhinged by frustration. “There were too many ups and downs, emotionally. It can happen – you play one set good, one set bad – especially on clay. But I was not happy on court and without reason. My team said: ‘Why do you have this attitude?’ They were right and I’ve always believed that if you want to improve you have to accept what you’ve done wrong.”

He praises his coaches, Simone Vagnozzi and Darren Cahill, both of whom he appointed in 2022. The Italian has instilled crucial technical changes while the steely Australian has strengthened his mentality. “After that match I worked out a lot,” Sinner says. “It’s OK to miss shots, even to lose. But you have to be happy to be on court.

“Tennis started off as my hobby and now it’s my job. But it’s important I still play like it’s my hobby. It’s impossible to always be positive. You have so many moments where you have negatives, but you have to find a way to get out of it. The more you play, the easier it is.”

There have been more scarring defeats. In 2022, Sinner had a match point against Carlos Alcaraz in their US Open semi-final before losing an epic battle that lasted more than five hours. At Wimbledon last year, he lost in straight sets to Djokovic, again in the semi-finals. But, since then, he recovered from triple match point down to defeat the seemingly indestructible Djokovic in the Davis Cup before sweeping him aside at this year’s Australian Open.

His new composure was tested in his first grand slam final when, in Melbourne, Daniil Medvedev cruised to a two-sets-to-love lead. But, rather than crumbling, Sinner grew stronger.

“It helped in the second set when I broke him the first time at 5-1 down. It gave me confidence that I can break him. I tried to stay focused and saw him going a little down physically. He had a tough two weeks playing very long matches. I tried to stay there as long as possible and get the momentum.”

Sinner has a curious phrase – “I like to dance in the pressure storm” – and he smiles. “You have to enjoy the pressure because it’s not like we are doctors doing surgery. You make a mistake as a doctor and it can cost a life. We just win or lose and next week you have another chance.”

On the night he became a grand slam champion, Sinner resolved to work even harder. “The work gave me this satisfaction of holding a big trophy. If you want to hold it again you have to keep working. There is no luck in the game. I have to improve physically and mentally and mix up my game because my opponents know me better now. It’s fun to find the solution.”

Did he allow himself to savour his achievement? “The best time I had was flying back with my team. I usually sleep on the flight – but not that night. The plane had a bar and we went there and talked. It’s what I like, sharing the victory with people who helped me get to this point.”

Sinner shakes his head cheerfully when asked if he sank a couple of beers. “My celebrations are different. If I have a good week, I always eat a hamburger with french fries, one Coke and tiramisu or ice cream. In Melbourne, I had everything. That’s my guilty pleasure.”

He looks very young as he laughs. But he carries a resilience forged when he left home at 14. Even a year earlier tennis had still been Sinner’s third-favourite sport behind football and skiing, where he was a national junior champion in giant slalom. He grew up in South Tirol in northern Italy, close to the Austrian border, where German is the local language. Sinner’s father was a chef and his mother a waitress at the ski lodge where they lived.

His parents allowed him to move 400 miles away to Riccardo Piatti’s tennis academy in Bordighera, on the coast near the French border. “It was tough, leaving home,” Sinner says, “but for them it was tougher, allowing their son to go away when he was so young. But they gave me that freedom.”

Sinner spoke little Italian when he arrived in Bordighera but he was lucky to move into the family home of the Croatian coach Luka Cvjetkovic. “I would do it all again,” he says, “because it helped me grow. You go to the supermarket, do your washing, clean up after cooking. These small things were important because, at 14, they mature you.

“I went through a tough time, leaving my home, my family, my friends, skiing and football. There were many things I gave up but it was good for me.

“It helped that, with Luka, I felt very safe. His daughter was five years younger than me and the son a bit smaller. I was like their older brother and they also had a dog. I love animals and we never had a dog because my parents were working so hard. The only problem was the communication because my Italian was not good and Luka’s wife and me used hand signs instead of talking. They were amazing and I don’t know where I’d be without them.”

He remains close to his parents, but as they are still working they won’t be in France. Sinner, however, appears to have recovered from the hip injury he suffered last month in Madrid. His record this year is an impressive 28-2 and on Monday he plays the American Christopher Eubanks, who is No 43 in the world and not a natural on clay.

Sinner won their only previous encounter in straight sets at the 2022 US Open but he says of Eubanks: “He’s very aggressive, a huge server, so hopefully I can return as many balls as possible and find a way from the back of the court. The hip feels good but I had nearly three weeks without touching the rackets. I lost weight but hopefully getting through the first round gives me time on the court and lots of confidence.”

If Sinner finds his ferocious rhythm, where he hits the ball as hard and with sweeter precision than anyone in tennis, he will be a serious contender for his second grand slam. His friendly rivalry with Alcaraz has emerged at just the right time as Rafa Nadal plays his final French Open and Djokovic struggles to regain his supremacy.

Sinner and Alcaraz, whose head-to-head record is locked at 4-4, are seeded to meet in the semi-finals. “When I play against him you know that’s a very important match,” Sinner says. “But we are so young and cannot be compared to [Nadal and Djokovic] yet. We have a long way to go and need consistency.”

He smiles when I ask whether he has worked out where he might find the best burger in town if he has another memorable tournament. “I haven’t reached that point in Paris,” Sinner says, “but I will try.”