Bulk Rename Utility

Alright fellas I got one for ya. I have 64 tracks all in numeric order, each track is a chapter in the audiobook I am combining into one file with chapter support. The problem is the audiobook only has 63 chapters. I know what caused the problem, the intro track that is not a chapter got counted as track 01. instead of being Track 00. So After changing the intro track number from 01. to 00. I need to shift the rest of the track numbers down.

How my files are currently numbered vs. how I need them numbered.
02 ---> 01
03 ---> 02
04 ---> 03
05 ---> 04
06 ---> 05

How can I use BRU to achive this?

The javascript can conduct any math against different parts of the filename, so the answers will depend on your filenames.
The other options could also conduct properly, but their settings will also depend on your filename-formats.