Connacht's Robbie Henshaw has been withdrawn from Ireland's tour to Argentina due to a hand ligament injury.
Henshaw sustained the injury earlier in the season and it had not limited his ability to train or play.
He exacerbated the injury in training this week and further specialist advice has recommended that surgical repair of the damaged ligaments should not be delayed further.
No decision on a replacement has yet been taken.
Henshaw is one of a number of candidates in line to replace Brian O'Driscoll in the 13 jersey for Ireland, following his retirement after winning the Six Nations.
Other contenders for the role include Fergus McFadden, Darren Cave and Jared Payne, the latter qualifying to play for Ireland next season.