[Steve Neul]

As bad as this spot is I can't see any other fix than to refinish the floor in the entire room. It would take too much sanding on that one spot to just touch up. If you just need to try to touch it up I wouldn't attempt to sand it, I would just get a can of Wood Classics polyurethane varnish and put a thin coat of varnish on the spot every evening and let it dry. Eventually you will get enough varnish on the spot it will hold together the loose pieces of wood and will stop further deterioration. Then someday when you are able, you can refinish the entire floor.

In the future if you don't put down a mat or rug, if you would just brush a coat of varnish on the floor under the desk once every couple of months you should be able to maintain the finish.

 

[Steve Neul]

If you managed to rent a good floor sander you could sand the floor and get some finish started over a weekend. The problem with working one spot is the color. If you just worked one end of the room you could never get the color to match. The wood and the old finish is yellowed and it would just show a line where you stopped. That is why I said if you were just going to touch up the spot not to sand it, but to just start putting varnish on it. It would just make the defect bigger. Also to sand that much in one small area you would be able to see a dip in the floor from across the room. You would need to sand a much larger area to feather out the dip.