Ireland forward Jamie Heaslip has been ruled out of the Six Nations match with England because of the back injury he sustained against France on Saturday.
The number eight had to be replaced in the second half after appearing to be kneed in the back by Pascal Pape.
Second row Pape was sin-binned and later cited over the incident.
Ireland reported that 31-year-old Heaslip has three damaged vertebrae and should be available to play again in approximately four weeks.
That means he will miss the visit of England to the Aviva Stadium on 1 March, but has an outside chance of recovering in time to face Wales in Cardiff on 14 March.
Ireland's final match of the Six Nations is then away to Scotland a week later.
|Ireland's 2015 Six Nations matches|
|7 February||Italy 3-26 Ireland|
|14 February||Ireland 18-11 France|
|1 March||England (h)|
|14 March||Wales (a)|
|21 March||Scotland (a)|
After last Saturday's match, French coach Philippe Saint-Andre said of Pape's challenge: "I don't think you can say it was deliberate."
Lock Pape was given a yellow card by English referee Wayne Barnes for the incident, which happened at a ruck in the 52nd minute.
Former Irish captain Heaslip struggled on until the 60-minute mark before being replaced by Jordi Murphy, but was said to be "in a lot of pain" after the match in Dublin.
Monday's medical report from the Ireland camp said Heaslip was feeling better.
"Although this injury causes a good deal of discomfort, it does not impact on the structural integrity of the spine, and once healed should pose no long term issues," it read.
"Typically this injury is treated akin to a soft tissue injury, according to symptoms.
"Jamie is already feeling more comfortable and it is hoped that he will be available to play again in approximately four weeks."