Bertranou started Argentina's first two matches of the championship against South Africa, including the 32-19 victory in Mendoza, but sat out last week's 46-24 loss to the All Blacks in Nelson.
The more experienced Martin Landajo was relegated to the bench to make way for the 24-year-old with former ACT Brumbies scrumhalf Tomas Cubelli dropping out of the matchday squad.
Ledesma also tweaked his front row after the Pumas were monstered at the scrum by New Zealand last week, bringing in Santiago Medrano at tighthead prop and switching Nahuel Tetaz Chaparro back to loosehead.
The third change was enforced by injury with Pablo Matera moving up from the bench to replace Tomas Lezana at blindside flanker.
Matera's elevation made way for the return on the bench of Juan Manuel Leguizamon, the 35-year-old veteran of 82 tests who last played for his country against Ireland last November.
Aside from the switch at halfback, the rest of the backline remained unchanged with prolific point scorer Nicolas Sanchez set to pull the strings of a dynamic attack from flyhalf.
Argentina have tasted victory in just one test against the Wallabies on Australian soil back in 1983 and have won one and lost two of their matches so far in the championship.
Team: 15-Emiliano Boffelli, 14-Bautista Delguy, 13-Matias Moroni, 12-Jeronimo de la Fuente, 11-Ramiro Moyano, 10-Nicolas Sanchez, 9-Gonzalo Bertranou, 8-Javier Ortega Desio, 7-Marcos Kremer, 6-Pablo Matera, 5-Tomas Lavanini, 4-Guido Petti, 3-Santiago Medrano, 2-Agustin Creevy (captain), 1-Nahuel Tetaz Chaparro.
Replacements: 16-Julian Montoya, 17-Santiago Garcia Botta, 18-Juan Pablo Zeiss, 19-Matias Alemanno, 20-Juan Manuel Leguizamon, 21-Martin Landajo, 22-Bautista Ezcurra, 23-Juan Cruz Mallia.
(Reporting by Nick Mulvenney; Editing by Ian Ransom)
