Alaalatoa was in the side to face Ireland at Suncorp Stadium in Brisbane Saturday, however, the Brumbies prop succumbed to a knock to his ankle sustained during training Thursday.
Australia have now added Robertson to the bench in response to the 24-year-old's injury, it was announced Friday.
Waratahs prop Robertson has not featured for the Wallabies since last year's clash with England at Twickenham in November.
#BREAKING | Tom Robertson called into the match day 23 after Allan Alaalatoa suffers a knock to his ankle. #AUSvIRL pic.twitter.com/sGpIjjDDJ5
— Qantas Wallabies (@qantaswallabies) June 8, 2018
Michael Cheika's Australia will come up against a new-look Ireland team, who are unbeaten since losing to Wales in March 2017.
Photo Getty Images. Caption: Australia prop Tom Robertson