Dublin - Ireland flanker Sean O'Brien was on Thursday ruled out of the Six Nations international against Scotland here on Saturday after a skin infection in his foot failed to heal as quickly as hoped.
His place on the Irish openside at Lansdowne Road will be taken by Munster's Peter O'Mahony, with Shane Jennings filling the bench spot vacated by O'Mahony.
Leinster back-row O'Brien was named European Player of the Year last season after starring for the Irish province in their European Cup-winning campaign.
His exit means Ireland will be without several key players this weekend.
Before this Six Nations Championship started, regular captain and star centre Brian O'Driscoll -- arguably Ireland's best player of the professional era -- was ruled out of the tournament with a shoulder injury.
And following last week's 17-17 draw away to France, Ireland saw stand-in skipper and key lock forward Paul O'Connell, the British and Irish Lions captain in South Africa two years ago, sidelined from the final two rounds of the Championship with a knee injury.
Scrum-half Conor Murray was likewise ruled out of the matches against Scotland and England (away at Twickenham) with a knee injury suffered in Paris.
One possible consolation for Ireland, however, is that they are now playing a Scotland side who will arrive in Dublin on the back of a run of five straight defeats dating back to last year's World Cup in New Zealand.
Ireland: 15-Rob Kearney, 14-Tommy Bowe, 13-Keith Earls, 12-Gordon D'Arcy, 11-Andrew Trimble, 10-Jonathan Sexton, 9-Eoin Reddan, 8-Jamie Heaslip, 7-Peter O'Mahony, 6-Stephen Ferris, 5-Donnacha Ryan, 4-Donncha O'Callaghan, 3-Mike Ross, 2-Rory Best (captain), 1-Cian Healy.
Substitutes: 16-Sean Cronin, 17-Tom Court, 18-Mike McCarthy, 19-Shane Jennings, 20-Tomas O'Leary, 21-Ronan O'Gara, 22-Fergus
Scotland: 15-Stuart Hogg, 14-Lee Jones, 13-Nick De Luca, 12-Graeme Morrison, 11-Sean Lamont, 10-Greig Laidlaw, 9-Mike Blair, 8-David Denton, 7-Ross Rennie, 6-John Barclay, 5-Jim Hamilton, 4-Richie Gray, 3-Geoff Cross, 2-Ross Ford (captain), 1-Allan Jacobsen
Substitutes: 16-Scott Lawson, 17-Euan Murray, 18-Alastair Kellock, 19-Richie Vernon, 20-Chris Cusiter, 21-Ruaridh Jackson, 22-Max Evans.