Robbie Henshaw will miss Ireland's Six Nations clash with France on Sunday.
The Ireland back has been ruled out through injury after his recovery from a dead leg took longer than anticipated.
Joe Schmidt had given Henshaw every chance to prove his fitness, taking the unusual step of delaying confirmation of his squad until this morning, but Sunday's game will come too soon for Henshaw.
The Leinster star has not featured since Ireland's 32-20 opening-round defeat to England, where he was deployed at full-back for just the second time in his Test career.
Sean Cronin has been dropped from the 37-man squad just a week after his first Six Nations start in 68 international appearances.
The hooker has been replaced by Ulster hooker Rob Herring.
There was better news for Joey Carbery, however, as the fly-half's recovery from a hamstring injury has progressed well enough to see him included.
Last week, Schmidt said if Carbery can train on Wednesday and Friday, he'll be considered for the squad to play France. The head coach has decided to add extra cover for the position, though, with Ross Byrne joining Johnny Sexton, Carbery, and Jack Carty in the squad.
Connacht scrum-half Kieran Marmion returns from injury to take his place in the squad ahead of his provincial teammate Caolin Blade.
Back-row Dan Leavy misses out, although his comeback from a calf injury continues to move closer. He will continue to increase his running volume outside of team training this week.
Schmidt will name his matchday-23 on Friday.