Australian travelling to Macau/HK/mainland China

I am an Australian tourist that's heading to Hong Kong for a few days. While there I will be taking a day trip to Macau before eventually leaving HK for Shanghai, PRC.

What I'm not sure about is.

If I enter either HK or Macau does that void or use up my one entry visa I've obtained for mainland PRC? Or will I be fine?

Thanks for your help!