Ireland head coach Andy Farrell selected youngsters Craig Casey and Jack Crowley as the half-back partnership for the Six Nations Grand Slam winners' first World Cup warm-up test with Italy in Dublin on Saturday.
Scrum-half Casey, 23, and 22-year-old fly-half Crowley know each other well as they play together at Irish province Munster.
Their form has been so impressive they have largely supplanted the more experienced pairing of fly-half Joey Carbery and scrum-half Conor Murray at their province.
Crowley started Ireland's win over Australia last November and he has a chance to stamp his mark as a potential successor to talismanic fly-half Johnny Sexton, who is due to hang up his boots at the end of Ireland's World Cup campaign.
Sexton is suspended for Ireland's three warm-up matches leaving Farrell a free hand to try out options of who should back the 38-year-old up at the tournament in France.
The Irish are in the tougher half of the draw as they bid to end years of under-achievement at the sport's quadrennial showpiece and get past the quarter-finals for the first time.
They have defending champions South Africa and Scotland in their pool and should they progress are likely to play either hosts France or New Zealand in the last eight.
Crowley, who will be winning his fourth cap, is vying with Ross Byrne for second choice to Sexton whilst Casey, starting for just the third time in his 11th Test, is competing with Murray as back up to first choice Jamison Gibson-Park.
At the other end of the experience spectrum veteran utility back Keith Earls will win his 99th cap as he starts on the wing.
The other wing will be Jacob Stockdale who gets the chance to reignite his career after slipping down the pecking order following injury. He makes his first appearance since the win over Japan in July 2021.
Second row forward Iain Henderson will skipper the side which has just three of the starters from the win over England that clinched the Grand Slam in March.
Two of them are in the back row -- Caelan Doris and Ryan Baird -- with the third player Robbie Henshaw in the centres, partnered by Stuart McCloskey.
The Irish move on from the Italy game to playing England in Dublin on August 19 and Samoa in Bayonne a week later.
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