Ulster outhalf Paddy Jackson will miss Ireland's summer tour to Argentina after suffering a stress fracture to his lower back.
Jackson had been named as one of two outhalves - first choice, Racing Metro's Jonathan Sexton is the other - in the Irish squad that will play two tests against the Pumas next month but his place will now go to Leinster's Ian Madigan.
The 22 year old Jackson had an ongoing issue with his back this season but the Ulster pivot was forced to limp off during last Saturday's RaboDirect Pro12 semi-final defeat to Leinster at the RDS, where he may have sustained further damage.
Jackson did not train with Ireland during a two-day camp Monday and yesterday, and on returning to Ulster sought medical advice which recommended that he withdraw from the tour to Argentina.
Jackson's misfortune means a call-up for Leinster's Ian Madigan, whom Ireland coach Joe Schmidt, had previously earmarked to travel with Emerging Ireland to a quadrangular tournament in Romania.
Munster's Ian Keatley and his provincial team-mate JJ Hanrahan are likely to make the trip to Romania.
Meanwhile Ulster are set to make a formal statement this week on speculation that Stephen Ferris will have to retire because of a long standing ankle injury.
