Replace a dot with a dash in date portion of album tag

I have searched around, but came up short. I know something needs to be done with the . (dot) to keep it from recognizing all characters, but the brackets, slashes and quotes are not giving me the result.

I have a large collection of live recordings and realized it is a little tough to look at with the current tag:

2011.23.09, The Orpheum, Boston, MA

looking for:

2011-23-09, The Orpheum, Boston, MA

Thanks Much and
Be Well

Create an action of the type "Replace with regular expression".
Enter as Search string:
Enter as Replace string:
Works if you have the date at the beginning of the string and a comma behind it.

Worked as described!!! Thanks so very Much