Paul Marshall will miss play-off chasing Ulster’s crucial RaboDirect Pro12 clash with Leinster at Ravenhill on Friday (live RTÉ Two, 7pm) due to an elbow injury.
The scrum-half damaged tendons in his right elbow in the act of scoring during last Saturday's Pro12 defeat to Connacht at the Sportsground.
Ulster will also be without suspended tighthead prop John Afoa, who is serving a four week ban for a dangerous tackle in Ulster’s Heineken Cup quarter-final victory over Munster at Thomond Park.
Ruan Pienaar and Ian Humphreys have been the favoured starting half-back combination and are likely to start again on Friday, but Marshall’s impact off the bench could be missed.
Tom Court may fill in for Afoa on the tighthead side.
With two games remaining in the regular Pro12 season, Ulster must beat runaway Pro12 leaders Leinster to sustain their bid for a play-off place and possibly set-up a final day "winner takes all" meeting Munster.
Glasgow are likely to claim one play-off spot with winnable matches against Benetton Treviso away and Connacht at home coming up in their final two games.
Ulster and Munster are due to meet at Thomond Park in the final round of Rabo Pro12 games and if Ulster can win on Friday, that match could determine which side secures a place.
Munster’s second-last game is against Llanelli in Wales on Saturday evening.