Q. Conventional tennis wisdom is that his genetic gifts — body type, natural grace — make it easier for him than others to stay healthy. True?

A. I hear that all the time. To have a potential is one thing, but to express it for 70 matches a year is something else. That’s Roger’s goal, to be consistent in each match and each training session. I think we underestimate all the work Roger does, and it’s a beautiful problem he has. We underestimate it because when we see Roger play, we see the artist who expresses himself. We forget almost that he has to work to get there, like watching the ballet dancer: You see the beauty but you forget the work behind it. You have to work very, very hard to be that beautiful a dancer.

Q. With the power and physicality of the modern game, speed seems critical.

A. You can’t forget we aren’t talking just about speed; we are talking about speed and endurance together. You don’t do one sprint like a guy who does the 100 meters. You go for three hours or more, stop and go. That’s very tough, but you have 25 seconds or 90 seconds to recover. In all the work you do, you have to stay aware of that. We don’t ask you to beat a speed record. We ask you to be fast repeatedly for a long time. That’s what makes tennis interesting. You don’t run 40 kilometers when a match lasts five hours. You run perhaps six kilometers at most.

Q. So has he lost a step?

A. I’m convinced that he has not lost a step. You also can’t forget that Roger has a quality of anticipation that is enormous. In tennis, you don’t only need to be fast. You need to run cleanly and use speed intelligently, and Roger is very intelligent in this department. It’s court vision, anticipation, maturity.

Q. Does Roger need to work as much physically as Nadal or Djokovic?

A. It’s not because his physicality is less in the forefront on the court that he doesn’t need to work at it. Roger varies play a great deal. So if you vary a lot it means you also have to have footwork that is more varied. That means you have to train to adapt to his type of game. It’s why it’s impossible to use one method with all the players. Federer is a different player than Nadal and Djokovic, but all three are champions.

Take someone who speaks English and French well and take someone else who speaks English, Russian, Japanese, Spanish and Chinese. Roger, for me, is the second one. He speaks lots of languages on the court with his creativity, but he also speaks lots of languages with his speed and coordination and his physique because he is obliged to do it because he is a creative player. What is more difficult? To speak seven languages or two? Seven, which proves that when you have lots of talent you have to work a lot, and that’s what Roger does. He wouldn’t be able to continue if he didn’t like it. You can work without really liking it when you are young because you are hungry. But when you’ve done it already and achieved a lot of things, you have to really truly like it because you know what’s coming. When you’re 23 and the fitness coach comes, you’re surprised. But when you’re 30 and the fitness trainer comes, you know what to expect, and Roger’s still smiling.

Q. How much of a challenge have Roger’s back problems posed?

A. No matter what it is — back, legs — it can be a problem. But Roger is also really good because he knows his body and is very good at communicating. It’s happened several times where he could tell us that he senses something wrong before there is a concrete problem. That helps us to anticipate.

Q. If Roger were not a tennis player what would be his best sport?

A. In soccer, he could have been really good. Roger has coordination from head to hands to feet. He could have been a good javelin thrower, he could have been good in basketball or volleyball or skiing because he has a great sense of balance. He’s very versatile. I think young players should draw inspiration from this because it’s like learning a language. When you develop a good, wide capacity for coordination when you’re young, it helps you express a lot when you’re older. Training for tennis shouldn’t be done in a tunnel. It should be in more of a courtyard.