Alexander Technique can be very effective in this kinda problem but some effort must be put in to reap benefits. it really makes you observe your own body by feel, thus ultimately improving proprioceptive capability. but how this is related to performance anxiety is one of the fascinating subjects of AT.
it is a mental problem but it's a part of the mind that's linked to the body and its control and AT elucidates how that connection can be exploited to our benefit.
compared to a professional performing artist performing a difficult piece in front of thousands of people, making the serve in is a walk in the park. to make this concise, the more you focus on the immediate execution as clearly as possible the less likely you'll make mistake under pressure situation. in this case you must know how to serve in as much detail as possible and clearly decide the target as early as possible. focusing on the details of execution usually takes a lot of pressure from the score or winning or losing.
to learn in more detail how all this work I recommend AT as well.
wanted to add that knowing the correct details of how involves understanding anatomy and biomechanics and the study of forms for activities and posture.
Last edited by boramiNYC; 12-07-2012 at 07:32 PM.