Pierre Paganini took part in track and field in his youth, and when he first decided to become a coach he was interested above all in working with soccer stars.
But it is in tennis, a sport he has never played regularly, where he has made an indelible mark as the key man in the shadows for Roger Federer and Stan Wawrinka.
If they have continued to win big into their 30s, it has a great deal to do with Paganini, the 60-year-old Swiss fitness coach who takes a cerebral approach to working up a sweat.
“A big part of the reason that I’m here where I am today is definitely because of Pierre,” Federer told me in a recent interview.