Rob Kearney could miss the rest of Ireland's Six Nations campaign after his arm injury proved more serious than first reported by Joe Schmidt.
The Leinster full-back damaged his bicep towards the end of Saturday's 63-10 win over Italy in Rome and the injury could require surgery in the coming days.
The Lion is set to miss Ireland's three-day camp in Monaghan and is in a race to be fit for the remaining Championship matches against France, Wales and England.
Simon Zebo would likely take over the No 15 jersey if that is the case, with fit-again Andrew Trimble coming on to the wing.
There is better news on Robbie Henshaw, who came off with a dead-leg last weekend and is set to train in Monaghan when the team get together tomorrow.
Peter O'Mahony trained with Munster yesterday, but will not play for the province against Ospreys on Saturday.
Munster director of rugby Rassie Erasmus said that his captain is almost ready to return from a hamstring injury, explaining: "He won't feature this week. He's still a week away. I think he might be ready next week but it would be stupid now to push that this week."
O'Mahony was one of a large contingent of Ireland squad members released to the provinces this week, with Ian Keatley, John Ryan and Billy Holland among those training at Munster, while Josh van der Flier, James Tracy, Luke McGrath and Jack Conan trained with Leinster.
Erasmus said that he was thrilled for Munster hooker Niall Scannell to step into the side when captain Rory Best cried off.
"He will get much more sterner tests. Italy away is probably not one of the toughest games that you play mentally, but physically it is very tough," he said. "But by that I am not by any way knocking Italy. I just think that playing France, playing England, those kind of games the pressure will probably be more.
"But he is overall a really calm and confident player and person. He was Ireland U-20 captain, so he has leader ability. So if he keeps his head and trains hard and stays focused he will play a lot for Ireland."
Erasmus dismissed reports that he is poised to add a French coach to his management team for next season.
Regis Sonnes, who coached in Bordeaux and also had stints with Agen and Narbonne, has been living in Bandon since last summer. Reports in the French media suggested he was to be added to the Munster coaching ticket but Erasmus said he didn't know him.
"I have never met the guy, I really don't know who he is, never spoken to him so it's definitely not true," he said.
Meanwhile, Leinster captain Isa Nacewa suffered a twisted knee in training last week but is expected to return to training later this week.
Read more here:
I'll stop short of saying they've repaid the debt in full, but certainly those given the chance to make good the loss in Murrayfield did so to telling effect. Rome wasn't built in a day, and certainly this squad has still a bit to go to get back where it was on that memorable afternoon in Chicago.