The Tykes will visit Champions London Wasps on Sunday without captain Mike Shelley who broken his thumb and will be out for up to six weeks.
New lock Clive Stuart-Smith is also out for between six and ten weeks with a knee injury sustained in the same game.
Commenting on the news Tykes boss Phil Davies said: "Mike has had a minor operation on his thumb today to fix that. To lose them both, on top of [injured squad members] Phil Murphy, Simon Halford and Tom Palmer, is a blow but we will have to re-group and prepare for Wasps. We will look at our options and make a decision on the squad as soon as possible and see if we have to bring in cover."
Shelley only missed one game last season and is the club's longest serving player whilst Stuart-Smith moved to Headingley in the close season from Gloucester.