Australia, who had lost 10 of their previous 11 ODIS against England, was in complete charge with the hosts now 26/3.
England have surged to the top of the ODI rankings on the back of aggressive run-scoring but the worry for Morgan’s men is that too many of their top-order appear to know only one way to bat.
Jonny Bairstow, for example, fell next to a careless hook off Behrendorff before Stokes and Jos Buttler (25) repaired some of the damage with a fifth-wicket stand of 71.
Earlier Finch, dropped on 15, and fellow opener David Warner (53) came through some testing early overs to share a stand of 123 as too many of England’s pacemen, with the exception of Chris Woakes, dropped short.
Finch went to his century thanks to a misfield by Woakes but next ball he miscued a hook off Jofra Archer and Woakes held the catch at fine leg.