Ireland captain Johnny Sexton has been ruled out of action for six weeks through injury.
The Leinster out-half sustained a twisted knee and ankle in the win over New Zealand, with an expected recovery time of up to 6 weeks.
It means he won't feature this weekend against Argentina - but he will remain with the squad.
Connacht's Jack Carty has been drafted in by Andy Farrell as a result, with Joey Carbery now primed to start Sunday's final Autumn test.
Gavin Coombes has returned to the squad following illness, which ruled him out of last weekend's win.
— Irish Rugby (@IrishRugby) November 15, 2021
Sexton is now in a major race against time to be fit for Leinster's opening fixtures in the Heineken Champions Cup.
Leo Cullen's charges are due to meet Bath on December 11th, before a clash with Montpellier six days later.
Those matches follow inter-provincial derbies against Ulster and Connacht in the United Rugby Championship.
Sexton's form for province and country has been superb so far this season.
Having made his 100th appearance against Japan last week, he was central to Ireland's win on Saturday against the All Blacks before being withdrawn late on.
His replacement Joey Carbery came on to nail some important kicks in the closing stages.
"If this is the peak, it is no good for anybody," Sexton said after the game, when asked about the significance of the result.
"This is the start of a two-year journey and it's important that we continue to improve.
"There is definitely room for improvement individually and you can see some of the stuff in the first half in terms of taking our chances.
"We could have scored a few tries in the first half. We need to keep our feet on the ground and keep improving.
"This is just the start and we need to keep building. The thing about beating New Zealand - it gives a lift to the country but you don't get a trophy."