Murray has a very difficult assignment next against 13th seed Matteo Berrettini but, with no sign of the cramp problems that had been bothering him this summer, the 35-year-old is feeling optimistic.
Speaking on court, Murray said: "Physically this is the best I have felt in the last few years. My movement is by far the best it has been in a long time, that has always been a really important part of my game.
"Nowadays, especially with a lot of the guys hitting a huge ball, you need to be able to defend well. I feel like I am doing that just now. I am getting closer to where I want to be and hopefully I can have a deep run here."
Expanding on what has changed later in the press room, Murray said: "My body is responding well to playing matches. It wasn't the longest match in the first round, but I pulled up pretty well from that one.
"Then today I think, physically, I was stronger than him at the end of the match, which is a really positive thing, obviously. My game improved as the match went on.
"My movement around the court is good right now. I feel like it's not that easy for guys to hit winners past me and I'm defending in the corners much better than I was 12 months ago here.
"I'm not having to worry about the next day waking up with something that is going to really impact me or hamper my tennis.
"When I played the match with (Yoshihito) Nishioka a few years ago here, I didn't recover from that match. It took me months. My groin and lower back flared up badly and it took a really long time to get on top of that and get better.
"I don't have any of those worries or concerns now. I wish I had won more matches this year. But being able to compete consistently, barring the little setback in the final in Stuttgart, has been good."