A teenage prodigy, Fitzgerald’s career has been dogged by injury with retirement a very possibility at one point in recent seasons and it is a medial ligament problem with his knee that will now force him into another bout of rehab for the next six-to-eight weeks.

Ireland team manager Mick Kearney has explained how he did the damage.

“Just doing a tackling drill at the Aviva (Stadium) on Friday in the open session and his foot just got caught in the grass and twisted his knee so fairly innocuous. He’s obviously very unfortunate to be out of the Six Nations. I suppose it could have been worse as well.

“He was very upset, to be honest with you and probably feared the worst. He has had a very good run injury-wise since the end of last season. He had a great World Cup and was flying for Leinster right through to the opening session on Friday so just one of those things.”

No replacement has been called up for Fitzgerald while the squad players who featured for the provinces last weekend - Finlay Bealham, Ultan Dillane and Robbie Henshaw for Connacht, Rob Herring and Luke Marshall for Ulster, James Cronin for Munster and Ian Madigan and Richardt Strauss for Leinster – are all fit and well on their return.

Ireland have been hit hard by injuries in the run-up to a tournament which they have won this past two years. Like Fitzgerald, Iain Henderson, Peter O'Mahony, Tommy Bowe and Marty Moore are all expected to miss the tournament in its entirety.

Leinster props Mike Ross and Cian Healy will also miss Sunday’s visit of Wales to Dublin at the least.