Leinster flanker Sean O’Brien has been ruled out for eight to 12 weeks after undergoing surgery on his broken forearm.
O'Brien sustained the injury in Ireland's 28-17 victory over Argentina earlier this month.
Centre Robbie Henshaw has also been ruled out for four to six weeks with a hamstring injury.
He suffered the injury in warm-ups for Ireland's win over Argentina and missed last weekend's 16-9 victory over the All Blacks.
Henshaw's injury further limits Leinster head coach Leo Cullen's options in the centre, with Joe Tomane ruled out last week for up to five months with a hamstring injury.
Flanker Dan Leavy will miss Leinster's PRO14 match against Ospreys on Saturday due to a neck injury.