Scotland coach Matt Williams has called openside flanker Andy Miller and Edinburgh scrum-half Rory Lawson for the game against the NSW Country in Wollongong.
The pair replace Mike Blair, who has been suffering with a shoulder strain all week, and Ben Hinshelwood on the bench.
Williams has already lost Cameron Mather and Euan Murray from the tour while full-back Robbie Kydd had a plate inserted just below his right eye socket after suffering a fractured cheekbone in Saturday's defeat to Queensland.
Miller played for Scotland's under-21s alongside current squad members Allister Hogg, Tom Philip and Chris Cusiter before moving to Australia in 2003 for a stint with club side Eastern Suburbs.
The 22-year-old will return to Scotland next season on a trial contract with The Borders.
Lawson, grandson of legendary commentator Bill McLaren, will sit on the bench in place of Blair but has represented Scotland from schoolboys through to the under-21s.
Scotland: G Morton; S Danielli, M Di Rollo, G Morrison, H Southwell; D Parks, G Beveridge; A Jacobsen, S Scott, J Brannigan, C Hamilton, S MacLeod, A Hall, S Gray, J Petrie (captain).
Replacements: R Russell, C Noon, A Kellock, P Dearlove, Andy Miller, R Lawson, S Cranston