JAMES O’Connor has already been ruled out of the Owls’ match at Oldham - a game that will see almost 5,000 away fans backing their team.
The Wednesday midfield battler suffered a nasty gash in his shin and missed the 1-0 FA Cup second-round win against Aldershot.
But such is the severity of the injury that manager Gary Megson is already resigned to being without him at Boundary Park on Saturday and is unsure how lengthy the lay-off will be.
“It’s a deep one, from just a collision in training,” admitted the Owls boss.
“We don’t know yet how long James will be out; it’s the sort of thing that could keep some players out for three months - but it won’t keep James out that long. He won’t be available for Saturday, though.”
The injury has ended a 12-match run in the side for the Dubliner who has been one of the surprise packages of the season.
He was always regarded as a central midfield player but has made a success of a right-side role, and has been praised by Megson for his tenacity, professionalism and workrate.
His place against Aldershot wasfilled by Chris Sedgwick, who scored two in a 3-2 win at Oldham in March.
Options for Saturday’s game will also include David Prutton, Jermaine Johnson and Liam Palmer, who started on the left flank against Aldershot in place of the ineligible Ben Marshall.
The team can expect the sort of vocal support that they enjoyed in last month’s 2-1 victory at Tranmere.
All 3,000 tickets in an initial allocation for the Boundary Park game were sold last week, and a further 1,615 have been sent to Hillsborough.
“Our fans are fantastic and hopefully we’ll get another good result for them on Saturday,” said Megson.
Prices are £23 adults, £12 over-65s and under-16s and £3 under-12s.
The Owls’ progress to the FA Cup third round means that their League One match at Scunthorpe on January 7 has been postponed.
The home pairing with West Ham means four successive Hillsborough matches.