Secrets of a True Master:
Introduction to My System
Welby Van Horn
At the advanced level, tennis has changed dramatically in the last 20-25 years. Semi-Western and Western forehands and two-handed backhands have become the norm. Players are also using much more body in their strokes.
On the forehand, tour players will sometimes rotate the shoulders up to 180 degrees on the forward swing. When they do this, the hitting shoulder will point to the net at the completion of the swing. The players are also "loading and exploding" as they first bend their knees and then push off the ground on the forward swing to generate additional force.
On practically every point world class players deviate from the fundamentals taught the beginner. A top player might jump off the ground to get a high ball into a better strike zone on a groundstroke. He might use an open stance to more quickly recover for the next shot (as opposed to the early-on fundamental of a "square" stance that I teach the beginner when learning the groundstrokes).