American champion Winder wins uphill finish, takes seven-second lead on GC with one stage remaining.
Spratt takes GC lead after beating Winder and Lippert in sprint.
Spratt takes third national title, Meyer becomes champion having narrowly missed out in 2019.
The Dutch were heavily favored to win Saturday, but no one expected a solo attack of more than 100km to succeed
Van Vleuten led home a Dutch one-two with van der Breggen in second and Australian Spratt taking third. U.S. rider Dygert Owen's attacking ride left her unrewarded in fourth place.
Michelton-Scott take one-two on GC and the sprint classification at home race.
Defending Tour Down Under champion Amanda Spratt retains race lead with only one stage remaining.