Sean O’Brien faces a “nightmare” six months sidelined with shoulder trouble that threatens to wipe out his Six Nations campaign with Ireland.
Leinster boss Matt O’Connor has revealed the British and Irish Lions flanker will undergo shoulder surgery in London on Friday.
The 27-year-old has suffered an infection in the same shoulder he had reconstructed after Ireland’s 24-22 Dublin defeat to New Zealand in November.
The bullish back-rower will miss Ireland’s three-Test autumn series and could now be left with just four international matches to prove his fitness for Rugby World Cup 2015.
“It’s a nightmare. He’s incredibly frustrated,” said O’Connor.
“There was a little bit of a complication with the previous surgery due to the infection.
“So they’re going to have to redo that reconstruction, which is a five to six month time frame.”
Ireland face South Africa, Georgia and Australia in their autumn Guinness series, and have just 12 fixtures before launching their World Cup bid against Canada in September 2015.
O’Brien has marked himself out as among the best flankers in world rugby through his gritty, physical style.
The 30-cap back-rower was expected to form a dangerous partnership with Peter O’Mahony and Jamie Heaslip for Ireland this autumn.
Now head coach Schmidt may well turn to Ulster flanker Chris Henry, who deputised impressively last term as Ireland claimed the Six Nations title.
Should O’Brien miss Ireland’s Six Nations campaign he would be left with just the World Cup warm-up fixtures to prove himself ready for the global tournament.
Ireland face Wales home and away and Scotland in Dublin August next year, before taking on England at Twickenham on September 5.
Schmidt’s men will line up against France, Italy, Canada and Romania in Pool D of next year’s England-based World Cup.
O’Brien swells Ireland’s list of autumn absentees after Munster duo Keith Earls and Donnacha Ryan were ruled out of November action this week.
Luckless Earls has undergone surgery on the patella problem that has dogged the versatile flyer for some time.
Lock Ryan could miss the entire campaign with a foot problem, while Ulster duo Iain Henderson and Dan Tuohy are also out of autumn contention.