Fergus McFadden suffered a broken thumb in Leinster's Champions Cup semi-final defeat to Toulon on Sunday and has been ruled out for the remainder of the season.
The Ireland winger will undergo surgery on the fracture on Wednesday morning and will be ruled out of action for eight weeks.
That means he will miss all of Leinster's remaining Pro12 matches this season and would theoretically next be available for selection the week of 15 June.
The injury severely damages his chances of being included in Ireland's Rugby World Cup squad, with Joe Schmidt's team next in action in a World Cup warm-up match against Wales on 8 August.
Other than McFadden's injury Leinster emerged unscathed from their Champions Cup exit to Toulon.
There was also news today on the province's long-term injury absentees.
Kane Douglas will undergo surgery this Thursday morning on the back issue diagnosed by a specialist last week; the injury will keep the Australian sidelined for up to three months.
Shane Jennings is still undergoing the return to play protocols and a final decision on his availability or otherwise will be made later in the week. Similarly Tom Denton, who was ruled out of the Toulon game with a bicep strain, will be assessed tomorrow.
Finally Kevin McLaughlin will take further contact this week as he recovers from his shoulder reconstruction and is in line to be available for selection before the end of the season.