Ulster scrum-half John Cooney has been ruled out of the team’s opening Investec Champions Cup game at holders Toulouse on Sunday (15:15 GMT).
The 34-year-old was forced off during last week’s loss to Leinster in Belfast with a hamstring injury.
Wing Ben Moxham is set for an extended spell on the sidelines. The 23-year-old was also injured in the Leinster game and will see a knee surgeon this week.
However, Ulster are hoping Zac Ward will return to training in time to make the game following concussion.
The club are short of fit wingers at the moment. Jacob Stockdale suffered a “significant” hamstring injury on Ireland duty last weekend, Robert Baloucoune is yet to play this season, and Aaron Sexton has departed to seek a career in the NFL.
Ulster confirmed their players who were involved in Ireland duty during the November Tests are available for selection.
Richie Murphy’s side will continue their European campaign after the Toulouse trip with games against Bordeaux, Leicester and Exeter.
Ulster lost 48-24 to Toulouse in Belfast when the sides met in last season’s Champions Cup.