Ireland winger Tommy Bowe will not be considered for the Six Nations game against Italy as he continues his rehabilitation after a groin injury.
The Ulster player was not included in a 33-man Irish squad for next Saturday's clash with the Italians in Dublin.
A statement from Ireland said that Bowe had "tightened up" after 30 minutes of Ulster's Pro12 win over the Dragons on Friday, having scored two tries.
Injury worries Peter O'Mahony and Jonny Sexton are named, as is Simon Zebo.
Luke Marshall, who began the opening Six Nations game with Scotland, is ruled out after suffering a concussion in the victory over the Dragons, but fellow centre Brian O'Driscoll is not regarded as a major doubt after overcoming cramp.
Bowe showed that he had lost none of his turn of speed as he scored two outstanding tries for his Irish province on his return to action after three months out with a groin problem.
He only played the first half however and according to the Ireland statement "will continue to follow a staged return to play programme" as he aims to recover full fitness.
The Lions back could still play a part in Ireland's final Six Nations match against France on 15 March.
Munster flanker O'Mahony is chosen in the extended squad, despite some lingering concerns over his ability to overcome a hamstring complaint.
Sexton is also an injury concern, but Ireland indicated on Thursday that he should be available for selection if he continues his present rate of recovery from a thumb injury.
Among those not considered for next weekend's game at the Aviva Stadium are Tommy O'Donnell, who received a stinger while playing for Munster at the weekend, Leinster scrum-half Isaac Boss and knee injury victim Felix Jones, who is replaced by Zebo.
Zebo is chosen in the panel for the first time in the present campaign, having returned to action with Munster in recent weeks following a calf injury.
Another notable inclusion is Ulster centre Darren Cave, who produced an impressive man-of-the-match performance against the Dragons, while Donnacha Ryan could challenge for a second row place after failing to make the match-day 23 which lost to England at Twickenham.
Ulster's Robbie Diack and Leinster hooker Richardt Strauss also join Joe Schmidt's squad.
Despite falling at the final hurdle in their bid to secure the Triple Crown, Ireland remain strong contenders for the championship as their points difference is presently superior to England, Wales and France, who have also won two of their three outings to date.