Back row forward Bryn Ward has been ruled out of Ulster's upcoming United Rugby Championship fixture against Munster due to a knee injury sustained during last weekend's 33-33 draw with Glasgow Warriors at Scotstoun.
The former Connacht player is not expected to feature in Saturday's match at the Affidea Stadium, which begins play at 17:30 BST.
Three other players have been confirmed as fit for selection following their recovery from previous injuries: Jacob Stockdale, Robert Baloucoune and Scott Wilson.
Stockdale has completed full training after overcoming a hip injury that previously required him to withdraw from the starting line-up against Glasgow.
Scott Wilson is cleared after an ankle injury, while Baloucoune is available following a concussion sustained in earlier competition.
For Munster, three key players remain unavailable ahead of the interprovincial encounter: Diarmuid Kilgallen with a hamstring problem, Michael Milne with an ankle issue and Fineen Wycherley with a shoulder injury.
Kilgallen and Milne both exited the field during the first half of Munster's victory over the Bulls in Limerick on Saturday.
Wycherley was withdrawn late in the game following his injury against the same opposition.
Scrum-half Matthew Devine is listed as doubtful for the clash at the Affidea Stadium, carrying a shoulder condition that requires further monitoring.
Devine's fitness status will be determined later this week before final selection lists are confirmed.
Diarmuid Barron, Jack O'Donoghue and Alex Nankivell are currently progressing through return-to-play protocols to ensure they meet medical clearance requirements.
Ulster head coach Richie Murphy has noted the positive progress of his squad regarding injury recoveries ahead of the fixture.
Munster secured their win over the Bulls in Limerick on Saturday after suffering a defeat to Glasgow Warriors at Thomond Park just seven days prior.
The Affidea Stadium will host the United Rugby Championship contest between Ulster and Munster this Saturday afternoon.