Ulster wing Jacob Stockdale will have an MRI scan on Monday to assess the extent of an ankle injury sustained against Leinster on Friday.
The Ireland international was replaced at half-time of his side's 20-13 defeat by their inter-provincial rivals.
Friday's injury was to Stockdale's right ankle and is unrelated to the left ankle injury that kept him out of all but one game last season.
Meanwhile, Rob Herring is following graduated return to play protocols.
The hooker was replaced in the first half of the Leinster loss after suffering a concussion.
Ulster are back in action in Belfast on Saturday night, when they host Ospreys who are coming off their first win of the season over Glasgow Warriors.
With Stockdale set to miss the fixture, Ulster will go into the game without their three first choice wings with Robert Baloucoune and Ethan McIlroy currently in South Africa with Emerging Ireland.
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