想要通过Windows批处理文件脚本重命名文件

Here is my file MY_APP_CON_123_yyyymmdd.hhmmss.txt where "yyyymmdd.hhmmss" is variable data. I want to rename it to MY_APP_CON_0123_yyyymmdd.hhmmss.txt (Zero infront of 123). When I use ren command as shown below, the first y disappears from the file name.Here is my file MY_APP_CON_123_yyyymmdd.hhmmss.