Ireland and Leinster number eight Jordi Murphy has been ruled out for up to nine months with an ACL injury.
Murphy scored his side's first try in their historic 40-29 victory over New Zealand at the weekend, setting them on their way as Joe Schmidt's side ended a 111-year wait to beat the All Blacks.
However, the back-rower was forced off during the match and the IRFU has now confirmed that the 17-time international faces a lengthy spell on the sidelines.
"Jordi Murphy leaves the squad after damaging the ACL in his left knee which rules him out of action for between six to nine months," read a statement.
"There were no other injury concerns to report from national camp following the game in Soldier Field.
"Niyi Adeolokun, Tiernan O'Halloran (Connacht), Dave Kilcoyne, Jack O'Donoghue, Darren Sweetnam (Munster) and Dan Leavy (Leinster) have joined the squad today at Carton House."
Ireland will face Canada in their second Autumn International on Saturday.
