arcgis desktop - Concatenating numbers and adding in leading zeros?

I have three text fields populated as follows: 1, 9, 1 that I need to concatenate into a field that looks like 01.09.01. Getting to 1.9.1 is easy but can anyone help out with how to formulate it so that each value has two places (i.e. add in those zeroes). I used to do this in Excel but can't figure out how to work in ArcMap 10.