Pumas replacement back Juan Imhoff has been ruled out of the clash with the Springboks in Mendoza on Saturday due to a quad injury.
The speedy wing suffered the leg injury at training on Thursday and as a result his place on the bench has been taken by Joaquin Tuculet.
According to Pumas doctor Guillermo Botto the Racing Metro flyer will be out of action for the next two weeks which means that he will not be fit for Argentina's next match against the All Blacks in Hamilton either.
The 24-year-old utility back Tuculet, who plays for Grenoble in the Top 14, will earn his sixth Test cap if he takes the field.
Argentina (revised): 15 Lucas Gonzalez Amorosino, 14 Gonzalo Camacho, 13 Marcelo Bosch, 12 Felipe Contepomi (captain), 11 Horacio Agulla, 10 Nicolás Sánchez, 9 Martín Landajo, 8 Leonardo Senatore, 7 Juan Manuel Leguizamón, 6 Pablo Matera, 5 Mariano Galarza, 4 Julio Farías Cabello, 3 Juan Figallo, 2 Eusebio Guiñazú, 1 Marcos Ayerza.
Replacements: 16 Agustín Creevy, 17 Nahuel Lobo, 18 Matías Díaz, 19 Tomas Lavaninni, 20 Benjamin Macome, 21 Tomás Cubelli, 22 Santiago Fernández, 23 Joaquin Tuculet.
Date: Saturday, August 24
Venue: Estadio Malvinas Argentinas, Mendoza
Kick-off: 16.10 (21.10 SA time; 19.10 GMT)
Referee: Steve Walsh (Australia)
Assistant referees: John Lacey (Ireland), Pascal Gauzère (France)
TMO: Marshall Kilgore (Ireland)