Ciarán Frawley requires surgery on his injured knee and will be sidelined for a "number of months", Leinster have confirmed.
The 24-year-old suffered the injury while playing for Ireland A against a New Zealand XV earlier this month.
"Ciarán Frawley will have a procedure tomorrow [Tuesday] for a knee injury and will be unavailable for a number of months," said Leinster in their weekly injury update.
It is dreadful timing for the versatile back, who impressed at out-half for the Ireland midweek team in New Zealand last summer and had been earmarked for a full Test debut this month.
Ireland centre Robbie Henshaw has returned to the province for treatment after suffering a reoccurrence of a hamstring injury during the opening five minutes of Saturday's game against Fiji.
There was some positive news on the injury front with Harry Byrne stepping up his rehabilitation from a hamstring injury. Fellow Ireland internationals Rónan Kelleher and Jordan Larmour are also closing in on a comeback from hamstring and foot injuries respectively.
However, back row Martin Moloney will miss the rest of the season with a ruptured ACL. The 23-year-old, who has made 10 appearances for the province, suffered the injury when introduced off the bench against the Scarlets last month.
Leinster face Chile at Energia Park on Friday.