Albornoz missed the trip to Australia after dislocating a finger on his left hand in the 29-23 victory over the All Blacks in Buenos Aires last month - Argentina's first ever win over New Zealand on home soil.
Carreras replaced Albornoz early in that match and steps up to start at North Queensland Stadium on Saturday with the uncapped Geronimo Prisciantelli backing up from the bench.
There were also two enforced changes in the matchday squad among the props after the retirement of loosehead Nahuel Tetaz Chaparro in the wake of the win over New Zealand and tighthead Pedro Delgado's move to England to join Harlequins.
Joel Sclavi is promoted from the bench to start at tighthead in place of Delgado with loosehead Boris Wenger included among the replacements and set to make his test debut.
Coach Felipe Contepomi also rejigged his back row with the inspirational Pablo Matera moving to number eight and Marcos Kremer coming into the starting side at blindside flanker.
Number eight Joaquin Oviedo drops to a bench featuring five forwards and three backs.
Contepomi said he had no hesitation in including two uncapped players in his squad for a match against a Wallabies team who beat world champions South Africa in Johannesburg in round one.
"We compete a lot throughout the week and our philosophy is to compete between us for the first part of the week and whoever we see that can represent us the best will play," he told a news conference on Thursday.
"If they have travelled with us to Australia, we are confident they can do their job, and whoever trains better will play. The competition brings the best out of them.
"We want to play against the best and we are lucky that we have the Rugby Championship to play the best in the world.
"You will always have a tough test for your first cap. We are confident in them."
All four teams have a win and a loss after the first two rounds of the competition but New Zealand top the table after earning two bonus points and Australia are second with one.
Argentina team to face Australia:
15-Juan Cruz Mallia, 14-Bautista Delguy, 13-Lucio Cinti, 12-Santiago Chocobares, 11-Mateo Carreras, 10-Santiago Carreras, 9-Gonzalo Garcia
8-Pablo Matera, 7-Juan Martin Gonzalez, 6-Marcos Kremer, 5-Pedro Rubiolo, 4-Franco Molina, 3-Joel Sclavi, 2-Julian Montoya (captain), 1-Mayco Vivas.
Replacements: 16-Ignacio Ruiz, 17-Boris Wenger, 18-Francisco Coria Marchetti, 19-Guido Petti, 20-Joaquin Oviedo, 21-Agustin Moyano, 22-Geronimo Prisciantelli, 23-Benjamin Elizalde.