Sean O'Brien's horrendous run of injuries shows no sign of abating, with Ireland head coach Joe Schmidt confirming the Leinster man broke his right arm in the 28-17 win over Argentina.
The Carlow native was playing his first Test for Ireland in almost a year after a slew of injuries sidelined the physical flanker.
He was replaced by Dan Leavy late in the first half after suffering the injury attempting to make a tackle.
"It looks like Sean has broken his right arm," Schmidt told RTÉ Sport's Clare McNamara.
"That is likely to keep him out of the game for a while. He is devastated, obviously. I though he'd had a pretty good start to the game. He was his physical robust self."
Schmidt then confirmed to Damien O'Meara of RTÉ Radio that the 31-year-old would undergo surgery.
Schmidt was happy to get the win but knows Ireland have lots to work on ahead of next Saturday's clash with world champions New Zealand.
"We did not have a huge amount of continuity in the first quarter. We were untidy from the first kick-off," said Schmidt. "We were a little bit inaccurate at lineout time but our scrum was really strong, so on the back of that we did get a bit of access into the game. We were happy with that.
"Argentina are very difficult to play against, very abrasive and it's hard to get quick ball against them."