Jacob Stockdale looks set to miss Friday night's Guinness PRO14 derby with Leinster at the RDS.
The winger-cum-full-back sustained a knee injury in last weekend's 15-10 victory over Munster at Kingspan Stadium.
Ulster say Stockdale will be assessed throughout the week, but it seems the top-of-the-table clash may come too soon for the 24-year old.
While fingers are crossed for a swift Stockdale recovery, Dan McFarland must plan without Sean Reidy for the next three months.
The flanker needed surgery to rectify a shoulder in Ulster's 38-34 defeat away to Gloucester last month in the Heineken Champions Cup.
McFarland is dealing with a lengthy injury list heading into Friday's game.
Jack McGrath, Iain Henderson, Luke Marshall, Rob Baloucoune, Rob Lyttle, Will Addison, Louis Ludik and Angus Curtis are all confirmed absentees.
Leinster have issues of their own following last week's loss to Connacht.
Jonathan Sexton and Scott Penny are undergoing return-to-play protocols having suffered knocks to the head last weekend.
There are also doubts over the availability of Ciaran Frawley and Josh Murphy - both late withdrawals from last weekend's matchday squad.
But Rhys Ruddock is fit again after a rib injury, and Jordan Larmour has stepped up his training regimen.