Ireland must do without the experience of Rob Kearney and Keith Earls in their World Cup opener against Scotland Sunday after the pair were unable to prove their fitness in time for Friday's team announcement.
Munster's Andrew Conway will take the place of Ireland's record World Cup try scorer Earls on the wing, while Leinster's 22-year-old flyer Jordan Larmour comes in for Kearney, who enters his third World Cup.
With 170 caps between the two injured men and influential centre Robbie Henshaw already ruled out, the Johnny Sexton-marshalled Irish backline will feature five World Cup debutants in Sunday's Pool A clash.
Kearney and Earls had mostly overcome their respective calf and knee issues, according to coach Joe Schmidt, suggesting the two will be fit for the next game against hosts Japan, along with recovering replacement fly-half Joey Carbery.
"Keith Earls was the sharpest player in training on Wednesday, so he's good, and Rob Kearney trained well, too," Schmidt told a news conference.
"So it was really just that we were getting very tight for time and the best continuity we had was to have the guys who trained through the time that we've been here.
"It's exciting to have the back three that we've got as well, it's a great opportunity and a fantastic challenge for them. Their enthusiasm is something that's contagious, their ability to get themselves into the game."
In the pack, Schmidt opted for a back row of Peter O'Mahony, CJ Stander and Josh van der Flier, while Iain Henderson will partner James Ryan at lock after what Schmidt described as a long selection discussion.
With the potential for Friday's sunshine in Yokohama to turn showery by Sunday and spoil Scotland's fondness for throwing the ball around, Schmidt insisted that Ireland had as much to fear from the Scots' kicking game if things get slippery.
"If Greig Laidlaw is at scrum-half, he's a very proficient kicker and when it does rain, points become that bit more valuable. We know Finn Russell has a huge variety of kicking game and there's the length of Stuart Hogg's kicking game, too," he said.
"I think in the end when you match it up for us, with the likes of Conor Murray and Jonathan Sexton, I don't think there's too much between the teams, wet or dry."
Meanwhile, Scotland named a largely expected line-up with considerable World Cup experience for Sunday's game.
Speaking ahead of the tournament opener, Scotland coach Gregor Townsend said: "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."
Ireland starting XV:
15. Jordan Larmour, 14. Andrew Conway, 13. Garry Ringrose, 12. Bundee Aki, 11. Jacob Stockdale, 10. Johnny Sexton, 9. Conor Murray; 1. Cian Healy, 2. Rory Best (C), 3. Tadhg Furlong, 4. Iain Henderson, 5. James Ryan, 6. Peter O'Mahony, 7. Josh van der Flier, 8. CJ Stander.
Replacements: 16. Niall Scannell, 17. Dave Kilcoyne, 18. Andrew Porter, 19. Tadhg Beirne, 20. Jack Conan, 21. Luke McGrath, 22. Jack Carty, 23. Chris Farrell.
Scotland starting XV:
15. Stuart Hogg, 14. Tommy Seymour, 13. Duncan Taylor, 12. Sam Johnson, 11. Sean Maitland, 10. Finn Russell, 9. Greig Laidlaw; 1. Allan Dell, 2. Stuart McInally (C), 3. Willem Nel, 4. Grant Gilchrist, 5. Jonny Gray, 6. John Barclay, 7. Hamish Watson, 8. Ryan Wilson.
Replacements: 16. Fraser Brown, 17. Gordon Reid, 18. Simon Berghan, 19. Scott Cummings, 20. Blade Thomson, 21. Ali Price, 22. Chris Harris, 23. Darcy Graham.