The 35-year-old equalled Steffi Graf's of 22 at Wimbledon last summer but missed out at the other majors, including Down Under where she was beaten in the final by Angelique Kerber.
With arguably the best women's serve of all-time and powerful groundstrokes, Williams has always been feared on the Plexicushion courts of Melbourne Park and she'll again start as favourite in 2017.
Most experts still believe that if the American plays at her highest level, she won't be beaten but a run of one title in the last five Slams shows her standards can slip.
She started her season with a shock loss to Madison Brengle in Auckland, admittedly in windy conditions which irked her. There should be no such problem in Melbourne where Williams starts as the one to beat.