Ireland and Scotland have named their teams to face each other in their opening World Cup pool game in Japan on Saturday, with Scotland going for experience Ireland selecting a unexperienced at full-back.
22-year-old Jordan Larmour will make just his seventh Test start when slotting into Ireland's starting XV with number one full back Rob Kearney unable to fend off his calf problem.
Andrew Conway will start on the wing with his Munster team-mate Keith Earls not fully fit after a thigh complaint.
Scotand coach Gregor Townsend meanwhile has opted to name an experienced line-up, as skipper Stuart McInally will lead out a team boasting 630 caps for the Pool A clash at Yokohama's International Stadium.
Exeter full-back Stuart Hogg and Saracens wing Sean Maitland return to the back three after missing this month's final warm-up Test against Georgia to partner Glasgow's Tommy Seymour.
J Larmour (Leinster), A Conway (Munster), G Ringrose (Leinster), B Aki (Connacht), J Stockdale (Ulster), J Sexton (Leinster), C Murray (Munster); C Healy (Leinster), R Best (Ulster, capt), T Furlong (Leinster) I Henderson (Ulster), J Ryan (Leinster), P O'Mahony (Munster), J Van Der Flier (Leinster), CJ Stander (Munster).
Replacements: N Scannell, D Kilcoyne (both Munster), A Porter (Leinster), T Beirne (Munster), J Conan, L McGrath (both Leinster), J Carty (Connacht), C Farrell (Munster).
Hogg; Seymour, Taylor, Johnson, Maitland; Russell, Laidlaw; Dell, McInally (captain), Nel, Gilchrist, Gray, Barclay, Watson, Wilson.
Replacements: Brown, Reid, Berghan, Cummings, Thomson, Price, Harris, Graham.
Ireland youngster to be tested
Ireland's Assistant coach Andy Farrell declared both Kearney and Earls "available for selection" on Wednesday, but Ireland have opted not to risk either senior star in their pivotal Pool A battle.
Larmour's toughest task could be to stay strong under the high ball, the much-vaunted young star needing to hit top form to match one of Kearney's chief assets.
Conway has impressed across Ireland's warm-up matches and has always proved hugely reliable under the high ball.
So the 28-year-old will doubtless be called upon to help Larmour cope with the expected aerial assault.
Garry Ringrose has edged out Chris Farrell to start at outside centre, with Robbie Henshaw missing out due to hamstring trouble.
Rory Best captains the side from hooker on his 121st cap, while Iain Henderson will partner James Ryan at lock, with Tadhg Beirne on the bench.
Jack Carty is preferred to Joey Carbery on the bench, but Joe Schmidt confirmed that Munster playmaker Carbery is fully fit.
Schmidt said Earls and Kearney are fit but had not quite shaken off their injuries to have enough training time to merit selection.
"Keith Earls was the sharpest player on Wednesday at training. He's good and Rob Kearney trained well as well.
"We were really just getting tight for time. The best continuity we had was to have the guys we'd had training through the time we were here.
"It's exciting to have the back three we've got as well. It's a great opportunity and a fantastic challenge."
Scotland full strength at half-back
The rest of the Scotland line-up sees former skipper Greig Laidlaw join playmaker Finn Russell at half-back, with centres Sam Johnson and Duncan Taylor the only backs to be reinstated from the 36-9 win over the Lelos.
Glasgow forwards Ryan Wilson and Jonny Gray are the only forwards to remain in the pack, which features six more changes from the Georgia win.
Allan Dell, captain McInally and Willem Nel form the front row.
Edinburgh lock Grant Gilchrist returns to partner the reinstated Gray in the second row, while the capital club's Hamish Watson and John Barclay join Wilson in the loose forwards.
"We've had a really productive week's preparation in Nagasaki ahead of our arrival in Tokyo, with our players adapting to the time zone and weather conditions out here in Japan," said Townsend.
"As we've got closer to the game our training has been more about fine-tuning the hard work that's gone in over pre-season into a focus for Sunday's game.
"Our team has a lot of experience playing together in major games for Scotland, with a bench capable of making a difference when required. That cohesion, experience and leadership is very valuable in a build-up to a match of this magnitude as well as during the 80 minutes on Sunday."
Townsend added: "In Ireland we face a quality opposition who, over the past number of years, have earned the right to be the number one ranked side in the world.
"We know them well and are well aware of the strengths they possess throughout their squad. We expect them to play very well, as they did in their most recent games against Wales, so only our best performance will do in order to win.
"The prospect of facing them in the opening round of a Rugby World Cup is a fantastic challenge for our players and supporters around the world."
Related Rugby World Cup links
- Rugby World Cup 2019 Hub Page
- Rugby World Cup: Tony Calvin's outright betting preview
- Rugby Union World Cup Guide - Fixtures, pools, history, odds and highlight video
- Rugby World Cup: Squads & team-by-team guide
- How the World Cup will be won
- VOTE: Who will win the World Cup
- QUIZ: Rugby World Cup
- RWC: View from the press box
- More Rugby World Cup news
- More Rugby Union news