Ulster will be without Jack McGrath, Sam Carter and Rob Lyttle for their Heineken Champions Cup showdown against Clermont on Friday night, with Ireland prop McGrath facing surgery on an injured thumb.
Dan McFarland's men earned a vital 17-16 victory at Bath in their opening match in Pool Three at the weekend but they came out of that bruising encounter with a few casualties.
Aside from McGrath, Carter dislocated his shoulder while Lyttle also picked up a shoulder injury.
Ulster said McGrath "will be monitored over the coming weeks" with Carter facing three months on the sidelines and Lyttle ruled out for six to eight weeks.
Tries in each half by John Cooney and Lyttle helped Ulster make it five straight wins against Bath in European competition. They'll be pumped up for the visit of Clermont but will have to utilise their squad for the clash with the Frenchmen.