Porte considers Tour unlikely, describes lockdown in Monaco as "a bit like torture."
The Tour Down Under has stuck to a tried-and-tested format for many years, but with a new race director in 2021, that template could change.
Porte gets off to strong start after difficult 2019 season as he hopes to stay clear of last year's health issues.
Matt Holmes won atop Willunga Hill having doubted his ability to match up in the WorldTour just 24 hours earlier.
WorldTour rookie Matt Holmes survives from breakaway to out-kick Porte on Willunga, Impey cracks and falls off GC podium.
Nizzolo takes first win for team under leadership of Riis, Impey sets up final-stage showdown with Porte.
Ewan unstoppable in sprint finish, Impey pulls back 3 seconds on Porte's GC lead
Porte rode clear from a strong chase group at the bottom of final climb, takes first strike in battle for overall.