Removing lighter mark from pine chest of drawers

[Merrow]

I have one of those pine chest of drawers that I suspect that everyone had at one point in their life! I was hoping to sand it down, wax it and replace the drawer knobs just for a bit of a change. I've been experimenting with one drawer before tackling the whole thing, but can't seem to get rid of the lighter patch where the knob was. Is it just a matter of sanding more? Worried I'll not have any drawer left by the end!

Pic to try and illustrate what I mean - the knob is the colour the whole front used to be.

You'd have to sand the rest of the drawer front down to the wood not affected by either the finish or exposure to light (or both). I would either use wood dye such as Colron to touch in the lighter area so it's less noticeable or just make sure that the new knobs cover it.

After an afternoon of sanding I'm going for knobs that cover it!