After the toss is complete the next step is to a) fully coil the upper body and legs, and b) have the racquet head pointing up to the sky. To fully coil, watch Ginepri slide his left hip towards the net, sink down with his knees toward the ground, and finally, fully coil his shoulders back and down. Notice in the final frame how his shoulders are coiled much more than his waist. This creates a kind of body "wind up". By rotating the shoulders more than the hips, you have wound up the body like you would wind up a clock. This is also referred to as the "pole vaulter" position. It looks like a pole vaulter before springing.

Please note that there has been absolutely NO SWINGING OF THE RACQUET. The racquet is actually being held back and delayed while the BODY coils up and stores energy. Remember that the power in the serve has almost nothing to do with the racquet until the end of the stroke. Instead it's the body that transfers energy from the core to the shoulder to the arm, and at the very end to the hand. You will see this even more clearly later on. But note for now how it is the body that has stored all the energy and the racquet is simply pointing to the sky. The racquet is the LAST LINK in the kinetic chain and is going to be passively pulled and lifted until the absolute end of the stroke. So for this first stage of the stroke, think "store up energy in my core and delay the racquet for later on".

Note the same above reference points in this clip of Johannson. Can you see how the shoulders have coiled back and down much more than his waist. This is body "wind up" in action. The perfect "pole vaulter" position. Notice as well how this coiling has caused his left hip to slide out into the court. And his knee bend has caused him to sink down into the ground. By coiling up and sinking down, pro servers have two huge sources of energy to release. They can uncoil and spring up. Two unwinding forces that will eventually be transferred to the hand on contact. Now you can practice winding up and sinking down with a delayed racquet head. Feel the potential energy being created.