Paddy Jackson insists his chastening Heineken Cup final experience last year has prepared him for his Ireland debut in Sunday's RBS 6 Nations clash with Scotland.

Uncapped Jackson has been selected ahead of Ronan O'Gara, the Munster veteran who is 14 years older and has made 127 Test appearances, for the pivotal clash at Murrayfield.

It was a major call for coach Declan Kidney, not least as the 21-year-old rookie failed to cover himself in glory during his biggest match to date, the 42-14 defeat by Leinster in the 2012 Heineken Cup final at Twickenham.

Having already experienced the roller-coaster of emotions in his blossoming career, Jackson insists he is ready for what awaits in Edinburgh.

"I've come a long way since the Heineken Cup final. I'll be more used to dealing with nerves and don't think I'll be as nervous," he said.

"After the Heineken Cup final I forgot about rugby for a while. I took a break, came back for pre-season and knuckled down.

"I'm excited and looking forward to getting out there against Scotland. I was very surprised to be selected, I had butterflies in my stomach, but then I calmed down.

"I'm really glad I've got my chance now. This will be the biggest game I've played in."

"I'm really glad I've got my chance now. This will be the biggest game I've played in." - Paddy Jackson.

Jackson will perform the kicking duties against Scotland, even though South African Ruan Pienaar fills the role for Ulster.

"I kicked for Ulster at the start of the season and felt as though it was a matter of keeping Ruan at bay for as long as possible," Jackson said.

"He's one of the best kickers in the world and has 10 or 15 metres on me.

"I sat down with (Ulster coach) Mark Anscombe and he said he wanted Ruan to kick. There's not much you can do about that, but I've still been training most days."

Jonathan Sexton's hamstring injury has given Jackson the chance to prove he belongs in the Test arena and ambition prevents him from being satisfied by performing a supporting role.

"We're all competitive rugby players and everyone wants the starting jersey.

"I know I'm young and coming through, but eventually that's where I want to get to," he said.

Jackson is joined in the starting XV by another uncapped Ulsterman in Luke Marshall, who replaces foot injury victim Gordon D'Arcy at inside centre.

Live RBS 6 Nations coverage on RTÉ Two from 2pm on Saturday 23 February and 1.15pm on Sunday 24 February (Scotland v Ireland). Live streaming Ireland only.

Live radio coverage of Scotland v Ireland on Sunday Sport on RTÉ Radio 1 from 1.50pm. Live streaming available worldwide.