Centre Jonathan Spratt has been ruled out of action after going under the knife to cure a back problem this week.
The twice capped Welsh international, 23, now faces a spell on the sidelines of around two months, as confirmed by Ospreys Physio, Chris Towers:
“Jonathan had surgery to treat a disc problem in his lower back on Wednesday. The early signs are that he is recovering well and will start some light rehab over the weekend. We have set a realistic target of getting him fit and playing again in around eight weeks.”