The concern over Rob Kearney's hamstring/lower back has been intensified by the news the Ireland full-back will miss out on the opening to close out the Six Nations against Scotland on Saturday.
This means Simon Zebo will almost certainly be handed the number fifteen shirt by coach Joe Schmidt.
Prop Cian Healy (hamstring) and scrum-half Eoin Reddan (calf) were scheduled to partake in training today to advance their claims from their recent injuries.
Wings Andrew Trimble and Keith Earls and centre Robbie Henshaw were all stitched up from various blood injuries to play their parts in full training yesterday.
Coach Schmidt included Munster full-back Andrew Conway, the ex-Blackrock College sensation, in an extended 35-man squad for the first time this week.
Loose-head Dave Kilcoyne has also been rewarded for his eye-catching return to form for Munster in the PRO12.
Ireland squad to prepare for Scotland:
Forwards (19): F Bealham, R Best, S Cronin, U Dillane, D Foley, C Healy, J Heaslip, D Kilcoyne, J McGrath, T O'Donnell, J O'Donoghue*, M Ross, R Ruddock, D Ryan, CJ Stander, R Strauss, D Toner, J van der Flier, N White;
Backs (16): A Conway*, K Earls, C Gilroy, R Henshaw, P Jackson, I Madigan, K Marmion, L Marshall, S McCloskey, F McFadden, C Murray, J Payne, E Reddan, J Sexton, A Trimble, S Zebo.
*Denotes uncapped player