Owen Farrell has been an ever-present for England since the summer tour to South Africa two years ago with Lancaster's steadfast belief in him as a "Test match animal" unwavering until this week.
But having started at fly-half against the All Blacks and Springboks and inside centre against Samoa, Farrell's lack of form has been evident and raised concerns over his fitness after struggling with a thigh injury earlier this season.
Lancaster came under pressure to axe Farrell after South Africa had prevailed at Twickenham and was subsequently forced to deny the player was undroppable.
Two further changes
Two further changes have been made to the starting XV that dispatched Samoa with Northampton forwards Dylan Hartley and Tom Wood restored to the pack.
Hartley replaces Rob Webber at hooker after being punished by Lancaster with demotion to the bench for receiving a brainless yellow card against the Springboks and Wood swaps places with James Haskell at blindside flanker.
Webber and Haskell are among the replacements with Lancaster having named an unchanged matchday 23.
“The Samoa game gave us the opportunity to give James and Rob a start and they made a good contribution,” Lancaster said.
“Tom and Dylan were disappointed not to be in the XV last week and they are desperate to go out and perform on Saturday so that we finish the series on a high.”
The stakes are high in Saturday's climax to the autumn at Twickenham with England needing to topple Australia to salvage respectability from an otherwise disappointing QBE Series.
The defeats by New Zealand and South Africa extended the team's losing run to five matches and while the mounting pressure was relieved with success against Samoa, the outlook for the month hinges on the result against the Wallabies.
England team:
M Brown (Harlequins); A Watson (Bath), B Barritt (Saracens), B Twelvetrees (Gloucester), J May (Gloucester); G Ford (Bath), B Youngs (Leicester); J Marler (Harlequins), D Hartley (Northampton), D Wilson (Bath), D Attwood (Bath), C Lawes (Northampton), T Wood (Northampton), C Robshaw (Harlequins, capt), B Morgan (Gloucester).
Replacements:
R Webber (Bath), M Mullan (Wasps), K Brookes (Newcastle), G Kruis (Saracens), J Haskell (Wasps), R Wigglesworth (Saracens), O Farrell (Saracens), M Yarde (Harlequins)
