It is important the set up, because the left hand here force the position of the right wrist setting up the position that will be maintained throughout entire the stroke (until impact).

So it is important that the standby phase you bring your racket at 90° in relation to the forearm (the paddle is pulled from his left hand, which brings the head of the racket close to his neck).

In fact, even before the opening, the left hand performs two operations:

1) bring the racket at 90° in relation to the forearm (the first movement of the wrist)

2) bend the wrist “backwards” [see following images].

The wrist holding this position until impact with the ball.

Note that this bend of the wrist allows the racket plate to be upright even when you have a “forced” grip.

position of the legs

The longer the trajectory of the racket before impact (of the “run-up”), the greater the force that moves the ball.

Putting yourself in the set-up position you notice as keeping the back leg besides the line perpendicular to the net (more towards the side fence that is on our right) leaves more space for the opening (the trunk is free to rotate to bring the racket more towards this fence netting).

Wawrinka always uses, for its winners, the position of the legs.