Leinster winger Luke Fitzgerald has been ruled out of Ireland's Six Nations campaign after sustaining a knee ligament injury in training.
The 28-year-old suffered the injury during Ireland's open session at the Aviva Stadium on Friday and could be out for two months.
Fitzgerald fell awkwardly after getting his foot caught in the ground.
"It was fairly innocuous. Luke is very unlucky to be out of the Six Nations," said team manager Mick Kearney.
"He is expected to be out of action for six to eight weeks and at this stage no replacement has been called in.
"He was just doing a tackling drill at the Aviva on Friday, his foot got caught in the grass.
"He was very upset and probably feared the worst."
Ireland are already without Ulster wing Tommy Bowe, a long-term casualty with knee trouble.
Coach Joe Schmidt can call on Andrew Trimble, Dave Kearney and Keith Earls for the wing, with Simon Zebo able to feature out wide or at full-back.
Ireland's first Six Nations match is at home to Wales on Sunday.