They were both competing in an ATP Challenger Tour event in Biella, Italy, in 2018. Lorenzi was the third seed, and Sinner, who was in qualifying as the World No. 878, had just turned 17.
“It was raining one day, so we went to another club to practise. We were doing a drill, and I was usually one of the best to do that drill from the baseline. He was doing that better than me, so when I finished I went to the coach and said, ‘This is special,” Lorenzi told ATPTour.com. “It is not normal when you are in the Top 100 to find a guy who is 17 and doing these things better than you. From then, I started to follow him.
“He’s a great guy and I still have a good relationship with him. What he’s doing this year is amazing and we hope he is going to do better and better in the coming years.”
In just three years, Sinner has gone from losing in the first round of qualifying at that Challenger to competing in the Nitto ATP Finals. With Matteo Berrettini’s withdrawal from the season finale due to injury, Sinner will take his place in the Red Group and face Hubert Hurkacz on Tuesday evening.
“I think it’s the best opportunity. Of course it came for Matteo’s injury. He doesn’t want to come in like this, but he deserved to be the first alternate,” Lorenzi said. “The crowd is Italian, so it’s an unbelievable chance for him. Usually he’d have to wait one more year to play this tournament and now he has the chance.
“Maybe he has less pressure because he’s playing at the last minute. I hope he can enjoy it and play great tennis, because the surface, fast, indoors, is one of the best for him.”
Sinner has already proven he can compete against the best players in the world. This season, he has won four ATP Tour titles and made his first ATP Masters 1000 final at the Miami Open presented by Itau.
“He’s going really fast, but for him I’m not surprised. I know it’s strange if he wins big tournaments [at his age], but what he is doing is normal because there are some players that have something more than others. He is one of them and I’m expecting a lot of things,” Lorenzi said. “I was with him when he made his first semi-final in Antwerp. We also made the semi-finals in doubles.
“He won his quarter-final, so the next day he had the first semi-final. After the quarter-final we played doubles and we won, but he just went to practise one more hour because he knew he had to improve. He is ready to be one of the best players in the world.”
It is easy to forget that Sinner, the 2019 Intesa Sanpaolo Next Gen ATP Finals champion, just turned 20 in August. He carries himself like an established veteran.
“It’s not easy. Sometimes we are not thinking that he is 20 years old. He has a lot of money for a guy of his age. A lot of people recognise him. He still continues to be a normal guy,” Lorenzi said. “Today we got lunch together and we were talking about anything, not tennis.
“He was just saying, ‘Maybe I have to do better next year. If I’m in the top eight I don’t have to wait for someone else’. That is the key to his level so young.”
According to Lorenzi, the former World No. 33 who retired at this year’s US Open and is in Turin for Sky Italia, Sinner has incredible technique and power.
“It’s like he has a different racquet from me. Last year in New York I was practising with him every day. After practising with him, everyone else was hitting too slow,” Lorenzi said. “The ball comes fast. He takes the ball earlier and he has such good technique that the ball is coming quicker from his racquet. I think a lot is his technique is perfect on court. He starts from the legs and then the body.
“Sometimes I watch his match and stand behind him. It’s like he knows where the ball is going and takes it earlier than everyone else.”
Lorenzi praised Sinner’s team, led by Riccardo Piatti. But he added that not everything the former junior skier does on the court can be taught.
“He is special,” Lorenzi said. “He can do things that for us are very difficult. If you watch him play, it’s simple.”