Ulster backs Luke Marshall and Louis Ludik are facing lengthy lay-offs after picking up injuries in last Sunday's Champions Cup play-off win over the Ospreys.
Their respective injuries look like being a massive blow for Ulster as both could be absent for most of the next campaign.
Marshall left the field on the medical cart after sustaining a knee injury during the second half of Sunday's season-ending clash which Ulster won 35-17.
It is thought that the 27-year-old Ireland international centre will require surgery after sustaining serious damage to his knee and is likely to be out for most of next season.
Ludik also departed the game at Kingspan Stadium in clear discomfort, though he was helped off early on.
The 31-year-old Irish-qualified South African utility back is thought to have badly damaged his hamstring.
Also rehabbing a knee injury is prop Tom O'Toole, who played for 80 minutes on Sunday after Ross Kane's late withdrawal.
The 19-year-old was withdrawn yesterday from Ireland's Under-20s squad for their World Championships in France.