Jannik Sinner feels that his physical and mental development have been crucial in him taking the next step at Grand Slam tournaments.

The 21-year-old has reached a career-high No. 8 in the Pepperstone ATP Rankings and lifted eight tour-level trophies. However, the Italian had lost in the quarter-finals at all four majors before his victory on Tuesday at Wimbledon against Roman Safiullin.

“For sure physically I have improved. I’m much stronger,” Sinner said after improving to 1-4 in Slam quarter-finals. “I can stay on court for many hours without suffering. Also mentally you’re going in a slightly different mental side on court knowing you are also Top 10 player. It is a little bit different. You might go as a favourite most of the time on the court until certain rounds of the tournament.

“Also this is different. I think game-wise or tennis-wise I feel better. If I have to play the slice, I can play now without thinking. Before [it] was always a little bit different. I can go to the net knowing that I have good volleys. I have some good things now in my game and hopefully I can use it in the right way.”

Sinner, who has dropped just two sets en route to the semi-finals, works with coaches Simone Vagnozzi and Darren Cahill. The Italian feels their team dynamic has been important in his recent success.

“The combination with Darren and Simone is very good. For sure Darren knows a little bit better how to behave in certain moments like this, something new for me. He knows how to deal with it because he had obviously other players who were much better than me,” Sinner said when discussing Cahill, who has coached Andre Agassi and Lleyton Hewitt.

“It is good to have him. He gives me a lot of confidence. He is also a very nice, nice person who you can smile and you can joke around [with]. But he always finds the right words, let’s say like this. Especially before the matches, he knows what to say, which makes me feel good.”

Sinner will continue the quest for his first major against Novak Djokovic on Friday. The 21-year-old, who lost in five sets against the Serbian last year at SW19, is excited for the challenge.

“It’s for sure one of the toughest, if not the toughest, challenge in front of me… It is a very, very important round, semi-finals,” Sinner said. “He has won 23 Grand Slams. [He] won in Australia, won in Paris. He is in a huge confidence boost also.

“It’s going to be tough, but I will obviously try my best. Last year I played a very good match against him. I have learned about it. Hopefully I can show this also on the court. I’m going to stick with my game plan in my mind, and hopefully I can execute it in the best possible way. So let’s see.”