Decks, Patios, Porches and Docks - Replace old deck post

I need to replace a 4x4 deck post (old one was eaten by termites). The problem is that it goes through the concrete patio (about 4 in thick) and I would not like to touch the patio around the post much. Otherwise the patio would look ugly.
So what would be the best way to do it?
Thanks in advance.

Support the beam or whatever this post is supporting by installing temporary posts on both sides of the bad one, leaving yourself enough room to work on it. Remove the old post, cutting it off about 6" or so above the concrete. Then remove the portion that is embedded in the concrete. Next. once you have everything dug out of the hole in the concrete, fill that hole with redimix and let it cure for several days. Once it's cured, attach a stand-off post base to the slab NEXT to where the old post was (NOT over your patch, but still directly under the beam) and install a new post.

Thanks a lot for the quick response!!!
You are referring to something like Simpson AB44, right?

The only concerns I have is if 4 in. of concrete is enough to support the post and it's not going to give out on me in a couple of years.
Thanks again.

Actually what you should do after you dig out the remains of the rotten post is dig down in the hole to below the frost line in your area and fill it with cement. Do not allow the existing patio to come in contact with the new cement, use a spacer. When the cement is cured drill a hole in the center and secure a deck post base support and attach your new post.