Pumas forced to change a winning side.
The Pumas claimed an impressive 22-20 victory over Eddie O'Sullivan's side in Santa Fe last weekend, but Loffreda has been forced to reshuffle his squad for the clash at the Jose Amalfitani stadium in Buenos Aires.
Trio Marcelo Bosch, Manuel Carizza and Martin Gaitan have all been recalled by club side Biarritz in order to take part in the Top 14 semi-finals.
Perpignan lock Rimas Alvarez and Hindu duo Juan de la Cruz Fernandez Miranda and Hernan Senillosa have been included in their places.
Squad: Agulla, Fernandez Miranda, Senillosa (all Hindu), Ayerza (Leicester Tigers), Schustermann, Bouza (both Leeds Tykes), Contepomi (Rovigo), De Vedia (Saracens), Durand, Todeschini (both Montpellier), Fernandez Lobbe (Sale Sharks), Fernandez Miranda (Aviron Bayonnais Rugby), Lozada, Gambarini (both CASI), Gonzalez Bonorino (Capitolina), Guinazu (Agen), Henn (Montauban), Leguizamon (London Irish), Leonelli (Glasgow Warriors), Serra (SIC), Vergallo (Jockey Club Rosario), Alvarez (Perpignan).