Leinster have confirmed that Garry Ringrose will be out of action for between four and five months.
The centre underwent an operation on a shoulder injury last week, according to the province.
Ringrose suffered the injury while on Ireland duty in Japan last month.
It means that Leinster will be without both Ringrose and Robbie Henshaw for the opening months of the season, while both are in a race to be fit for the autumn internationals.