Glasgow Warriors have been dealt a triple injury blow with flanker Rob Harley expected to be out for up to eight weeks.
Harley suffered knee ligament damage in training while prop Ed Kalman has undergone back surgery and Pat MacArthur has a fractured foot.
Kalman sutained his injury in pre-season, MacArthur was injured in the defeat by Scarlets.
Warriors head coach Gregor Townsend is seeking his first win of the season.
"We're clearly disappointed to have lost our opening two matches, and there's a determination about the whole group to achieve a win this weekend," Townsend said ahead of the trip to Ospreys.
"To do that away from home against a quality outfit like Ospreys, we know our performance will need to be spot on in all the key areas," he added.
"In both the Ulster and Scarlets matches, we've done certain things very well, but haven't been as accurate as we know we can be in other facets of the game."