Joe Mattock has become the latest Wednesday player to face a long lay-off.
Tests on his injured thigh have shown that he has torn a muscle.
Manager Stuart Gray confirmed: “He went for a scan and he has a tear in his quad - he’s expected to be out for a lengthy time.”
Gray does not expect Reda Johnson to be ready for Saturday’s match at Yeovil so Jeremy Helan is likely to fill the left-back spot.
The Owls boss always regards injuries as bringing opportunities to others and has managed to engineer a revival in the team’s fortunes despite a series of blows.
Players badly affected recently have included Johnson, Michail Antonio, Kieran Lee and Jose Semedo,
Lesser problems have hit Glenn Loovens and Oguchi Onyewu, but there have been long-term ones this season for Lewis Buxton, Anthony Gardner, Kamil Zayatte, David Prutton and Martin Taylor, stretching back to the part of the campaign when Dave Jones was manager.
Mattock took over from Johnson and has missed only one of the last 10 games, through suspension. He went off in last week’s match against Middlesbrough.