Keith Earls has been forced to withdraw from Ireland's team for Sunday's Six Nations clash against Wales.
Earls has remained at home in Limerick because his recently-born daughter is unwell so Leinster's Fergus McFadden has been called into the team.
McFadden now partners Gordon D'Arcy at centre in the absence of Brian O'Driscoll, who will miss the entire Six Nations because of injury.
Dave Kearney, brother of Rob Kearney, is drafted into the replacements.
Ireland team manager Michael Kearney said that Earls "is in hospital as we speak".
"The nature of the illness is unclear, however I did speak to Keith this morning and he was hopeful and optimistic that the baby would get home some time over the weekend," added the Ireland manager on Friday afternoon.
"The decision was taken following a conversation with Declan (Kidney) and Keith yesterday and it was thought that it was in the best interests of Keith and his partner Edel and their families that Keith remains in Limerick for the weekend."
In Wednesday's team announcement, In-form Ulster winger Andrew Trimble was selected on the left wing, with Jonathan Sexton starting at fly-half in preference to Ronan O'Gara.
Conor Murray plays at scrum-half, with the uncapped Peter O'Mahony named among the replacements.
The Ireland pack is unchanged from the eight selected in the defeat by Wales in the World Cup quarter-final in New Zealand in October.
Paul O'Connell captains the side in the absence of O'Driscoll.
Munster flanker O'Mahony was only called into the senior squad earlier this week.
Ireland coach Declan Kidney has kept faith with Donncha O'Callaghan despite strong claims by Donnacha Ryan for a starting place.
Ireland: R Kearney; T Bowe, F McFadden, G D'Arcy, A Trimble; J Sexton, C Murray; C Healy, R Best, M Ross; D O'Callaghan, P O'Connell; S Ferris, S O'Brien, J Heaslip.
Replacements: S Cronin, T Court, D Ryan, P O'Mahony, R O'Gara, E Reddan, D Kearney.