Chris Henry and Keith Earls have been ruled out of Saturday's November test against Australia.
Henry suffered a suspected hamstring tear in the weekend win over Samoa, while Earls has failed to recover from a knee injury.
Shane Jennings and Luke Fitzgerald have been called up to the squad instead.
Tommy Bowe is also a doubt, after going off injured on Saturday with a tightness in his leg.
Jonny Sexton should be available for selection after overcoming a hip injury, as should Paul O'Connell, Sean O'Brien and Cian Healy, who all came off the bench at the Aviva Stadium on Saturday.
Coach Joe Schmidt says Ireland cannot afford to make the same mistakes against Australia as they did against Samoa, warning that the kicking game must improve
Meanwhile, Ireland are the biggest movers in the IRB world rankings after last weekends win over Samoa.
Joe Schmidt's side are up two places to 6th, with Australia remaining in fourth.
World Champions New Zealand are still top of the pile ahead of their visit to the Aviva in 2 weeks.
©INPHO/Dan Sheridan