Wallabies coach Joe Schmidt has called up Hamish Stewart, Darby Lancaster, Tom Hooper and Harry Hoopert from the Australia XV squad for the last two matches of the end-of-season tour against Scotland and Ireland.
Stewart, who played at flyhalf and centre for the XV side as they drew 10-10 with Bristol and lost 38-17 to England A, offers additional cover in the midfield with Samu Kerevi facing a ban after being dismissed in the win over Wales last weekend.
Additionally, Kerevi and lock Will Skelton are likely to be unavailable for the match against Ireland in Dublin on November 30 because it falls outside the international window.
Flying winger Lancaster, who made his test debut against Georgia in July, adds another outside back to the squad after Dylan Pietsch suffered a calf injury in the tour-opening win over England.
Uncapped forward Hoopert bolsters the stocks of loosehead props after veteran James Slipper lasted only 20 minutes as a replacement against Wales, forcing starter Angus Bell to return for a second stint.
Flanker Hooper started every Wallabies match at last year's World Cup and came off the bench against Georgia and South Africa earlier this year.
Centre Josh Flook, another of Schmidt's new caps this year, was added to the squad last week after Pietsch returned home to begin his rehabilitation.
Australia's impressive wins over England and Wales mean they are on course for an unlikely Grand Slam if they can beat Scotland and Ireland.
No 8 Harry Wilson, who captained Australia against England, should be available to face the Scots at Murrayfield on Sunday after missing the Wales clash because of concussion.
Tighthead prop Taniela Tupou also missed the Cardiff match with a knee injury and looks unlikely to play in Edinburgh, but scrumhalf Jake Gordon could return despite sustaining a nasty gash to his head against the English.