Basically it's my aim in this piece to construct a fight scene, whereby the attack has just landed a punch on his opponent square in the face.
However, I can't seem to get the anatomy correct

and after toying around with it until i could take no more, I decided to ask for some help here.
Here's where I am at so far, any help would be extremely appreciated and i look forward to your feedback!

and here is a reference image I've been loosely working from:

Thank you again!