Luke Fitzgerald has been ruled out of Ireland's RBS 6 Nations campaign with a medial ligament injury.
The Ireland and Leinster back picked up the injury during an open training session on Friday at the Aviva Stadium when his foot became caught in the ground and he fell awkwardly.
A scan has confirmed the bad news and Fitzgerald is expected to be out of action for up to eight weeks.
The 28-year-old has earned 35 caps for Ireland and played for the British and Irish Lions against South Africa in 2009. No replacement for the Leinster man in the squad has been named yet.
"He was just doing a tackling drill at the Aviva on Friday, his foot got caught in the grass," said Ireland's team manager Mick Kearney.
"It was fairly innocuous but very unfortunate and he's very unlucky to be out of the Six Nations."
"He was very upset and probably feared the worst. He'd had a very good injury run recently, had a great World Cup and was flying for Leinster."
Ireland head coach Joe Schmidt is already also without winger Tommy Bowe, who misses the tournament with a knee injury, but will be able to call on the likes of Andrew Trimble, Dave Kearney, Keith Earls and Simon Zebo, who signed a new two-year deal to remain at Munster on Monday.
Schmidt has no other fresh injury concerns as his squad gather in Carton House to prepare for their tournament opener with Wales on Sunday.
The team to start against Wales will be confirmed at lunchtime on Friday.
Ireland v Wales is live on RTÉ2 and RTÉ Radio 1 from 2pm on Sunday and there will be a live match tracker on RTÉ.ie/sport
