Oh great! There is a new king in tennis. The great Andy Murray is now number one of ATP. After a long period of Djokovic`s supremacy, coaches and players have a new model to follow. Is that how it is supposed to be? Or independent of who is number one in the world, the best techniques or fundamentals depend only on the best bio-mechanics? Unless the number one has invented a new technique that has never been used before and it is physics compatible, I mean, bio-mechanically compatible, the answer to that question is NO! Should I imitate his service? Should I switch my backhand and cut my back swing? How low should my gravity center be when running side ways? His grip is slightly different from the former number one, it seams more efficient. Should I try this new grip? Again, the answer is NO! But if are capable enough to make a bio-mechanics analysis, if you know advanced physics to understand vectors, forces, alignments, torsion, inertia, strength transference, potential energy, kinetic energy, basic vector operations (adding, subtracting, multiplying and dividing vectors in multidimensional space), potency, synchronicity, etc., then you really are ready to do it. If you can not do it, you might have at maximum a non grounded opinion. And that is very dangerous. Your strokes might be getting worse and you don´t know it. Depending on how long and how charismatic the number one is, he can influence not only a few players, but a whole generation of them. In the 60´s the western grip became the grip of the moment. Everybody was explaining how it worked and how good it was. And it is now very clear that it was a great mistake. When Nadal was number one, every kid in the world was trying to copy his racket pull up on the forehand. Does it make any sense? Does it have any bio-mechanics efficiency? NO, it does not! Physics is not adaptable, it is unique no matter who the player is. There is absolutely no two different movements on a stroke to produce the same result. The player might use different ways as a result of some physical restrictions or any needed adaptation. Otherwise, all of them should be searching for the perfect mechanics, as close as possible to the perfect fundamental. Adaptations should not be taught to kids, no matter what! Use physics as model to teach young players.