The pair replaced Nahuel Tetaz Chaparro (34, ruptured Achilles) and Santiago Grondona (25, knee), who have picked up long-term injuries and are out of the September 8th-October 28th tournament.
Argentina have been training in Portugal and travel to their base in France on Friday.
They beat Spain 62-3 in a final warm-up last weekend, but it came at a cost with Grondona rupturing anterior cruciate ligaments in his left knee.
Coach Michael Cheika’s side are in Pool D and open their campaign against England in Marseille on September 9th. Japan, Samoa and Chile are also in their group.