Leinster back-row Rhys Ruddock has been drafted into Ireland's squad as John Muldoon's replacement for Saturday's clash with Argentina in Dublin.
Muldoon tore his medial knee ligament in last weekend's 53-0 win for the Ireland XV over Fiji in Limerick and is expected to be sidelined for up to three months.
Fly-half Jonathan Sexton is expected to be fit for the Pumas clash despite suffering a groin injury in the warm-up for the Fiji match which ruled him out of the encounter.
He will not train fully until later in the week but is expected to be declared fit for the Pumas' visit.
"During the warm-up he got a bit of a tight groin so we felt it was prudent to pull him out," said Ireland coach Declan Kidney.
Ireland will name their team on Thursday.