Robbie Henshaw's World Cup could be over, with Ireland head coach Andy Farrell speculating his centre could be sidelined for a minimum of two weeks.
Henshaw picked up a hamstring issue in training earlier this week which ruled him out of contention for this Saturday's Pool B decider with Scotland, as Stuart McCloskey comes in to take his place on the bench.
The Irish management team are waiting to make a decision over Henshaw, and will assess the situation further if they get past Scotland this weekend.
"He pulled up with a hamstring unfortunately at the end of the session on Tuesday," head coach Andy Farrell said.
"The diagnosis with hamstrings, they want to see how things settle down and it probably takes about five days for that type of thing to happen but it looks like it could be a minimum of a couple of weeks at this stage.
"We'll assess that as we go, certainly he'll be around, rehabbing and we'll see how the weekend goes with other injuries, etc and we'll assess how Robbie's going along the way also."
Farrell has made two changes to his starting side for this weekend, with Dan Sheehan and Iain Henderson (below) coming into the side, while Rónan Keller and James Ryan drop down to the bench.
Ryan's training at the end of last week was impacted by a hand injury picked up in the win against South Africa, but Farrell maintains his second row is fully fit.
"He is, he's fit. He had a bit of a niggle on a wrist but that's fine and trained the house down, actually trained the best I've seen him in train in a good amount of years yesterday.
"He actually nearly took Johnny's [Johnny Sexton] head off three or four times so he's fit and raring to go, there's no doubt."
McCloskey's promotion to the bench gives the Ulsterman a first potential appearance at the tournament.
It's been a hectic fortnight for the 31-year-old, who raced back to Ireland following the win against South Africa on compassionate leave for the birth of his second child.
And Farrell says he's deserving of his chance to make a mark at the tournament, after staying patient for the first four weeks.
"He's been excellent, as has everyone else that's not played as much game-time as they'd possibly have wished for.
"His attitude has been top-drawer, the message to those guys has been all along that you've got to be ready and your attitude has got to prove that, day in, day out.
"It certainly has as far as everyone's concerned, Stu is one of those who is ready to slot in and is ready to slot in."
Ireland will guarantee progress to the knock-out stages with a win or a draw.
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