Ireland will have to do without Jonathan Sexton and Mike McCarthy for next week's Six Nations match against Scotland.
Fly-half Sexton has failed to recover the hamstring problem that forced him off against England last Sunday.
Second-rower McCarthy also picked up a knee ligament injury during the 12-6 defeat in Dublin forcing team manager Mick Kearney to announce that the pair will miss the upcoming trip to Edinburgh.
"Jonny's scan revealed a grade two hamstring injury. Progress has been good so far, but it's too early to say when he will return to play," Kearney said.
"Mike has hurt the medial ligament of his right knee. It's quite sore and he will be in a brace for two weeks. A further review will take place in two weeks."
Ireland will also be without Cian Healy for the next two matches after the prop was banned for three weeks for stamping on England's Dan Cole.