Perhaps a better way to describe the player who is “unconscious” is by saying that his mind is so concentrated, so focused, that it is still. It becomes one with what the body id doing, and the unconscious or automatic functions are working without interference from thoughts.
The ability to approach this state is the goal of the Inner Game. The development of inner skill is required, but it is interesting to note that if, while learning tennis, you begin to learn how to focus your attention and how to trust in yourself, you have learned something far more valuable that how to hit a forceful backhand. The backhand can be used to advantage only on a tennis court, but the skill of mastering the art of effortless concentration is invaluable in whatever you set your mind to.
W. Timothy Gallwey