Ulster fly-half Paddy Jackson has been ruled out of Ireland's summer tour to Argentina because of a back injury.
Jackson has been diagnosed with a stress fracture in his lower back.
He has been battling the problem for some time, but the injury has got worse in recent weeks and he will miss the two-Test series against the Pumas next month.
Jackson's misfortune is good news for Leinster No 10 Ian Madigan, who has been called up to replace him.
Madigan was originally selected in the Emerging Ireland squad to tour Romania this summer but will now take Jackson's place in the senior squad.
Coach Joe Schmidt is taking just one other fly-half on the tour, Racing Metro's Johnny Sexton.
Ulster and Ireland hope rest will resolve Jackson's issue, and are keen to avoid the 22-year-old having to undergo surgery. He is expected to make a full recovery for the start of next season.
Ireland will play Tests against Argentina in Resistencia on June 7 and Tucuman on June 15.