The Ireland captain has been diagnosed with a twisted knee and ankle that will rule the Leinsterman out for a period of four-six weeks.
Such a timeline appears to also rule Sexton out of Leinster’s upcoming interpros against Ulster and Connacht, as well as the province’s opening European clash with Bath.
Connacht’s Jack Carty has been called up as cover, but it is largely expected that Joey Carbery will now start against the Pumas next Sunday.
The Munster outhalf played a pivotal role in the dying stages of the New Zealand win, kicking three late penalties – including one form halfway – to seal the result.
Gavin Coombes has also returned to the Ireland camp after recovering from illness.