Ulster skipper Johann Muller has been ruled out for the remainder of the season after injuring his bicep in Saturday's Heineken Cup defeat to Saracens at Twickenham.
The lock tore a ligament and was replaced by Robbie Diack with a quarter of an hour left in the 27-16 defeat.
The injury setback is a major blow for the Ravenhill outfit who cannot dwell on their European exit as they gear up for their final three RaboDirect PRO12 games.
Mark Anscombe’s men currently sit second in the PRO12 table and will be looking to secure home advantage in the league play-offs with wins over the Dragons, Connacht and Cardiff.
Prop John Afoa will miss Friday's game against the Dragons after returning to New Zealand for a week to spend time with his new-born daughter Violet.
Meanwhile, a medical report on Luke Marshall is pending after the young centre took a knock in the Saracens game.