Irish Rugby have confirmed that Joey Carbery suffered a fractured wrist during Saturday's November Test victory over Fiji at the Aviva Stadium.
The 22-year-old has been ruled out of this week's game against Argentina and could be facing a recovery period of six-to-eight weeks.
A number of other players have bumps and bruises, but all are expected to be fit to train in the coming days.
Leinster senior coach Stuart Lancaster feels Carbery was unlucky to get injured.
“If you watch Owen Farrell, if you watch Johnny Sexton, if you watch Joey Carbery, they all take it to the line and that’s the risk they run as a playmaker at ten,” said Lancaster.
“It was a really unfortunate one. He got some big hits and some hits in that Fiji game were as big as I’ve seen. He was unfortunate on that one really.”