Sinner, who first broke into the top 10 in 2021 but reached a career-high number eight in April, produced power that belied his slender frame in a 6-4, 3-6, 6-2, 6-2 win over Russian Roman Safiullin (25) to emerge as a first-time major semi-finalist.
"For sure, physically I've improved. I'm much stronger. I can stay on court for many hours without suffering," Sinner, who has worked with former Australian player Darren Cahill this summer, told a press conference.
"Also mentally, you're going in a slightly different mental side on court knowing you're also a top 10 player. It's a little bit different. You might go as a favourite most of the time on the court till certain rounds of the tournament.
"I think also 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 bit different. I can go to the net knowing I have good volleys.
"I have some good things now in my game and hopefully I can use it in the right way."
In the semi-finals Sinner will meet holder Novak Djokovic, who fought back from two sets down to outlast the Italian in the quarter-finals last year.
"It's one of the toughest, if not the toughest, challenge in front of me... as I said before, it's a Grand Slam," Sinner said shortly before Djokovic beat Andrey Rublev to set up the clash.
"It's a very important round, the semi-finals. He's won 23 Grand Slams. Won in Australia, won in Paris. A huge confidence boost.
"It's going to be tough, but I'll obviously try my best, no? Last year I played a very good match against him. I've learned about it. Hopefully I can show this also on the court.
"I'm going to stay or I'm going to stick with my gameplan in my mind and hopefully I can execute it in the best possible way. So let's see."
