Jared Payne is likely to miss the start of next year's Six Nations after being ruled out of action for three months.
The Ulster centre sustained a kidney injury in the win over Australia in last Saturday's final Autumn International and the IRFU said: "He is expected to be out of the game for at least three months."
Payne went into Ireland's slender victory over the Wallabies on Saturday carrying what assistant coach Andy Farrell termed a "lower-limb tweak".
The influential midfielder shrugged off that problem to pass late fitness checks, but was later withdrawn at half-time.
Ireland boss Joe Schmidt described Payne's injury as "a decent whack in the ribs" in the wake of his side's win over the Wallabies.
But now it looks like he will certainly miss the majority of the forthcoming Six Nations championship.
His Ulster teammate Andrew Trimble has also been ruled out for a number of weeks due to a foot tendon injury he suffered in that same game.
In better news for Leinster the IRFU say Rob Kearney was removed from the Australian tie simply "as a precaution".