Hello - I am travelling from Sydney to Shanghai on the 27th of December

and will be in Shanghai for 4.5 days before leaving for USA on January 1st 2017. I am an Australian citizen. I wasn't able to find any information about the 144hr visa free exemption on the Sydney China Visit Centre website and am quite anxious about being denied boarding the plane in Sydney. Am I eligible for the 144-hr free exemption? Thanks!