Stephen Ferris is the latest confirmed absentee for Ireland's crucial clash against Argentina on November 24 after his ankle injury proved to be more serious than initially feared.
And scrum-half Eoin Reddan is unlikely to be considered for the non-cap international against Fiji on Saturday after sustaining an ankle injury.
Ulster back-row Ferris was hopeful of returning to the side this month but that ambition was dashed over the weekend, as was the prospect of Paul O'Connell appearing.
Donnacha Ryan and Cian Healy have been cleared to return to training after undergoing the required concussion testing.
Both players sustained impact injuries during the 16-12 defeat to South Africa, when Ireland's collective performance fell well below the level of some significant individual displays.
Stephen Archer, Tom Court, Devin Toner, Craig Gilroy, Paul Marshall and Roger Wilson have been called up to the training squad ahead of Saturday's game in Limerick.
Defence coach Anthony Foley has declared that Ireland will treat the Fijians with the utmost respect as Ireland reel from a run of five successive Test defeats, a record that will remain unchanged regardless of this weekend's efforts.
"Nobody likes losing," he said. "Sometimes you have to look at the manner of it. The manner of the 60-0 loss in New Zealand and Saturday's loss were completely different, chalk and cheese.
"There's a few issues we need to iron out. We need to make sure we build some momentum for this game.
"We are preparing like a Test match. It is no different to how we prepared last week – same meetings, same intensity and when we train we will have the same vigour.
"Obviously there will be different requirements from different players. The important thing is this is another Test match week for us and we make sure everybody is equipped properly for Fiji.
"They will punish you if you give them an opportunity. Our job is to make sure they get no opportunity."