Scrum-half Conor Murray's place in the Ireland starting team to face Scotland looks assured as Eoin Reddan is rated "highly doubtful" with a calf strain.
The pair were competing to wear the number nine shirt in the Six Nations opener in Dublin on Sunday.
Irish coach Joe Schmidt has called Leinster's Isaac Boss into his squad, and also has Connacht's highly-rated Kieran Marmion available if required.
British and Irish Lion Murray started two of Ireland's autumn internationals.
The Munster pivot was selected in the starting XV to face Samoa and New Zealand in Dublin, with Reddan getting the nod for the clash with Australia in November.
Despite Reddan's likely absence, Murray believes he still has a battle on his hands to secure the scrum-half berth.
"The pressure is just the same as before - Bossy's there and Kieran Marmion is knocking around as well," said Murray.
"To be honest, I'm just trying to focus on my own game and make sure I'm as sharp as I can be so I'm ready to go if I get the nod.
"There are three or four players vying for each position, so I'm just trying to look after my own corner and make sure I can give everything I can."
Murray expects Scotland counterpart Greig Laidlaw to set the tempo for Scott Johnson's side in Dublin.
Admitting Ireland must shut down the Edinburgh playmaker and goal-kicker, Murray said: "I rate him highly as a player, he's the focal point of their team, he drives a lot of their plays.
"I've played against him quite a bit against Edinburgh and a couple of times against Scotland.
"We'd like to think we know a bit about him but that doesn't make it any easier to stop him so we've got to be focused."
Cardiff's Munster-bound loose forward Robin Copeland has kept his place in Ireland's training squad after impressing in last weekend's 14-8 Wolfhounds victory over England Saxons at Kingsholm.
Murray hailed the back-rower as a good signing for Munster for next term, but also someone who could yet force his way into Six Nations action this term.
Head coach Schmidt is expected to start Chris Henry at openside flanker in place of the injured Sean O'Brien, which frees up a loose forward slot on the bench, and Murray sees no reason why Copeland cannot fit that bill.
"I've had a few chats to him since he's been in camp," said Murray.
"He's picked up three man-of-the-match awards for Cardiff in the Heineken Cup group stages, which is unbelievable.
"And up close he's a real athlete, a powerful player and he seems to be a natural footballer.
"It's a good signing for Munster and he's already having an impact here now as well."
Murray revealed that Ireland have analysed their last-gasp 24-22 defeat to New Zealand from November in a bid to stamp out little errors that cost them victory in such a cruel fashion.
Keen not to linger on that All Blacks epic, the 24-year-old British Lion said: "That consistency element has definitely been a topic of discussion for a long time in our camp now.
"It was a great performance against New Zealand, we came agonisingly close and we don't want to dwell on it for too long, but we must look back and draw on the positives too.
"I know a lot of rugby has been played since then, but that's still our last performance.
"We've looked at that game in detail, identified areas where we could have improved and we've got to take that forward now."