Jordan Larmour is set to miss the resumption of Ireland's Six Nations campaign, as well as the entire upcoming Autumn Nations Cup.
Independent.ie understands that Larmour is facing up to 10 weeks out with the shoulder injury he picked up in Leinster's win over Benetton on Saturday.
It is believed that Larmour dislocated his shoulder and is now facing a lengthy spell on the sidelines.
The news will come as a devastating setback for Larmour, who looked set to play a key role for Ireland over the coming weeks.
The 23-year-old was replaced after 48 minutes in Treviso, and needed oxygen to alleviate the pain to his shoulder caused by making a strong tackle.
"Jordan has taken a pretty heavy bang to his shoulder so we’ll get him assessed," Leo Cullen said immediately after the game.
"You could see he was in a fair degree of discomfort and stayed down for a while. We will get him scanned when we get back and we'll see the extent of that then."
Andy Farrell will be forced to call up a replacement for Larmour ahead of this week's Ireland camp, as preparations begin for the Six Nations clash with Italy on October 24.
Farrell's back-three options will be tested with Keith Earls also ruled out with a back problem.
Dave Kearney is back in training and could be an option, while the likes of Rory O'Loughlin, Mike Haley and Rob Lyttle will also be hoping to catch Farrell's eye.
A full squad update is expected from the IRFU in the coming days.