Tommy Bowe will not be on Ulster duty against his former club on Friday night at Ravenhill.
Instead, the ex-Ospreys ace is expected to return to action the following weekend when Ulster host the Scarlets.
Winger Bowe has been sidelined since picking up a groin injury at the end of October.
Ireland team manager Michael Kearney broke the news yesterday at Carton House where Joe Schmidt's men are encamped ahead of Saturday afternoon's RBS 6 Nations head-to-head with Wales.
Running through the injury list and the state of readiness of those working their way back to fitness, Kearney said: "We went out this morning and a couple of guys didn't train. Cian Healy, who put in a fairly heavy shift at the weekend, stood out of the actual running part of the training, but he did some scrummaging.
"Also Rob Kearney stood out of training this morning; he took a kick to his calf (against Scotland) so he didn't participate at all but he will train, hopefully, on Thursday.
"In relation to the few injuries that were around last week, neither Eoin Reddan nor Luke Fitzgerald are available for selection this weekend. They're just continuing their recovery and would hope to get some game time with their province (Leinster) next week.
"The same goes for Tommy Bowe and Donnacha Ryan. Neither of them will play for their provinces (Ulster and Munster respectively) this weekend but they'll get game time next weekend.
"In relation to Paul O'Connell, while he observed training this morning he didn't participate. He is still recovering from a very heavy chest infection, but he is making progress and again we would be hopeful that he will train on Thursday."
Having played Scotland on Sunday, the six-day turn-around before facing the reigning champions at the Aviva Stadium means Ireland having to manage their schedule carefully and cleverly. Today is another rest day for the players.
Manager Kearney explained: "The squad came into Carton House last night (Monday) and had a fairly light run out this morning – mainly organisational – for about 30 minutes.
"With the challenge of the six-day turn-around, rest and recovery were the key elements; that has been a major concentration for the strength and conditioning staff during that time."
Meanwhile, forwards coach John Plumtree stressed the need for up-front superiority.
"If you're going to win this competition I think the greatest set of forwards is certainly going to contribute to winning it," said the Kiwi, who was head coach of Super 15 outfit Natal Sharks from 2008 until last summer when Joe Schmidt brought him on board to work with the Irish forward players.
"If you have the better pack at the weekend also you get a better opportunity to win that game.
"In my mind Irish forwards are good but they're not great and that was where we wanted to go.
"We have some really good individuals in that pack but to become great you've got to work hard together and that was the challenge I dished out to them," said Plumtree.