Quinn Roux was not included in Ireland's Six Nations squad when coach Joe Schmidt announced his initial 38-man selection last month, but the Connacht lock is now set to assume a pivotal role in their must-win encounter with Scotland.
Called into group after injuries to Iain Henderson and Tadhg Beirne, Roux has moved further up the pecking order after Devin Toner was ruled out with an ankle injury in their opening round defeat by England in Dublin.
Connacht's Ultan Dillane is also part of the Irish squad but Roux remains the favourite to make his first Six Nations start on Sunday after a third championship appearance off the bench against England.
"Quinn has really stepped up in terms of calling the lineouts, leading the team and on the field, he's slotting in when he's had to pretty well," Ireland scrum coach Greg Feek told reporters.
"He's good in the scrum and mauling. As a tight forward he ticks a lot of the boxes. Luckily for us, we have good depth there at the moment."
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A defeat at the first hurdle of the tournament comes as a reality check for some of the players in the Irish dressing room.
For Bundee Aki, Jacob Stockdale, James Ryan, Joey Carbery and Jordan Larmour, it was their second loss on the international stage, while it was a first for Andrew Porter and John Cooney.
"They probably haven't had the adversity that I as a coach, along with Joe and a lot of the other players, have been through before. It does build a bit of resilience," Feek added.
"Everyone is quite hard on themselves in terms of losses as well. We all put our hands up and say 'we didn't do this right or that right'.
"Again, you don't survive in this environment if you can't handle the pressure. You've almost got to look at it, hold on to it and run with it; you know?"
