Ireland centre Gordon D'Arcy has been ruled out of Saturday's RBS 6 Nations game against Scotland at Murrayfield.
The Leinster player, 25 on Thursday, has been struggling with a hamstring injury.
D'Arcy will now join international and club team-mate Brian O'Driscoll on the sidelines.
Ireland coach Eddie O'Sullivan said: "We gave Gordon a chance but it didn't work out.
"In terms of the risk element, it was a sensible precaution.
"He should be fine for the next game but we do not want to tempt fate."
Shane Horgan will move to centre from the wing with Kevin Maggs promoted from the bench. Girvan Dempsey will move to the wing from the bench.
But O'Sullivan has prepared his team for the loss of the key centres this week.
He added: "We have been practising with this line-up through the week just in case."
Munster lock Paul O'Connell, who is making his 25th international appearance, will captain the side in O'Driscoll's absence.
Revised Ireland team:
G Murphy (Leicester); G Dempsey (Leinster), S Horgan (Leinster), K Maggs (Ulster), D Hickie (Leinster); R O'Gara (Munster), P Stringer (Munster); R Corrigan (Leinster), S Byrne (Leinster), J Hayes (Munster), M O'Kelly (Leinster), P O'Connell (Munster, capt), S Easterby (Llanelli), J O'Connor (Wasps), A Foley (Munster).
Replacements: F Sheahan (Munster), M Horan (Munster), D O'Callaghan (Munster), E Miller (Leinster), G Easterby (Leinster), D Humphreys (Ulster), G Duffy (Harlequins).
After Ireland's heroic big-game hunt of the Springboks and Scotland's six-try runaround of the Pumas, the challenge of engineering the most spectacular win of the autumn series now falls on Wales, writes Peter Jackson.