Dublin - Paddy Jackson is set to make his Ireland debut against Scotland on Sunday after being selected ahead of veteran outside-half Ronan O'Gara for the Six Nations match at Murrayfield.
Ireland coach Declan Kidney had to find a new starting No 10 after first-choice fly-half Jonathan Sexton suffered a hamstring injury during the 12-6 defeat by England last time out at Lansdowne Road earlier this month.
But rather than recall O'Gara, Ireland's most-capped player with 127 Tests behind him and the man who came off the bench to replace Sexton against England, Kidney sprang one of the biggest surprises of his five-year reign as national coach on Wednesday by opting to start Ulster's Jackson in Edinburgh.
O'Gara, 36 next month, was on the bench.
Also making his Test debut this weekend will be Jackson's fellow Ulsterman Luke Marshall, in at inside centre after the experienced Gordon D'Arcy was ruled out with a foot injury.
O'Gara, for several seasons Ireland's first-choice outside-half, has played back-up to Sexton since the 2011 World Cup.
However, his form this season has been modest with O'Gara failing to sparkle against England and below his best playing for provincial side Munster against Llanelli last weekend.
"Paddy's inclusion was a challenge given the stature of Ronan O'Gara, but I think Paddy deserves a go in this one," Kidney said.
"It was a very difficult decision to leave Ronan out, it was right up there. But that's a compliment to Paddy."
Ireland were forced into making five changes after injuries took a toll of their side in a bruising defeat by England in Dublin and Kidney, turning to Marshall, said: "Luke was with us all through November and accomplished himself very well."
Elsewhere in the backs, left wing Simon Zebo's tournament-ending foot injury led to a recall for utility back Keith Earls.
Meanwhile, the pack showed two changes, with Tom Court replacing Cian Healy after the loosehead prop was suspended for stamping on England's Dan Cole and experienced second row Donncha O'Callaghan coming in for Mike McCarthy, out with a knee injury.
Ireland, one of four teams along with Scotland boasting one victory and one defeat after two rounds, need to win at Murrayfield to maintain their hopes of winning the Six Nations title.
Even before the Championship started, Ireland suffered a huge double blow when both lock Paul O'Connell and wing Tommy Bowe were ruled out of the entire tournament, with the loss to England compounding their injury problems.
But the good news for Ireland was that star centre Brian O'Driscoll (ankle) and flanker Sean O'Brien (hamstring), who both suffered injuries against England, were declared fit to start against the Scots.
Scotland, who beat Italy 34-10 at Murrayfield in the second round, made just one change to their starting side earlier Wednesday when prop Geoff Cross was recalled in place of Euan Murray, whose Christian beliefs mean he refuses to play on Sundays.Teams:
15 Stuart Hogg; 14 Sean Maitland, 13 Sean Lamont, 12 Matt Scott, 11 Tim Visser; 10 Ruaridh Jackson, 9 Greig Laidlaw; 8 Johnnie Beattie, 7 Kelly Brown (captain), 6 Robert Harley; 5 Jim Hamilton, 4 Richie Gray; 3 Geoff Cross, 2 Ross Ford, 1 Ryan Grant
Substitutes: 16 Dougie Hall, 17 Jon Welsh, 18 Moray Low, 19 Alastair Kellock, 20 David Denton, 21 Henry Pyrgos, 22 Duncan Weir, 23 Max Evans
15 Rob Kearney; 14 Craig Gilroy, 13 Brian O'Driscoll, 12 Luke Marshall, 11 Keith Earls; 10 Paddy Jackson,9 Conor Murray; 8 Jamie Heaslip (captain), 7 Sean O'Brien, 6 Peter O'Mahony; 5 Donnacha Ryan, 4 Donncha O'Callaghan; 3 Mike Ross, 2 Rory Best, 1 Tom Court
Substitutes: 16 Sean Cronin, 17 David Kilcoyne, 18 Declan Fitzpatrick, 19 Devin Toner, 20 Iain Henderson, 21 Eoin Reddan, 22 Ronan O'Gara, 23 Luke Fitzgerald