Lees' absence leaves struggling pair Glenn Loovens and Joost van Aken as Wednesday's primary centre-back options, with the untested Frederico Venancio and left-back Daniel Pudil likely to back them up until Sam Hutchinson returns from a long lay-off of his own, hopefully, in time for the new year.
But with the Owls' back line uncharacteristically porous even with Lees fit this season, it would be no surprise to see them enter the market for reinforcements in January.
Though, with little money to spend, Carlos Carvalhal's side would have to be shrewd. That in mind, here are three players they could potentially sign on the cheap.
John Egan (Brentford)
Brentford's captain has stood up to the plate since the sale of his former partner and ex-Wednesday target Harlee Dean in August and has reportedly caught the eye of Sheffield United. The Daily Mirror reported last month the Blades 'may bid £750,000' for Egan this winter and Wednesday would perhaps be wise to get involved if he is, indeed, available at that price. You may recall him scoring in a 2-1 win for the Bees at Hillsborough last season.
Paul Huntington (Preston North End)
Only four Championship teams have conceded fewer goals than Preston this season and Huntington is a big part of that. The 30-year-old is out of contract next summer (although Preston do have an extra year's option, according to Transfermarkt) but may be tempted by the idea of a fresh challenge after five and a half seasons at Deepdale. Formerly on the books of Newcastle and Leeds, Huntington should be able to handle the pressure that comes with playing for a club of Wednesday's stature.
Tosin Adarabioyo (Manchester City)
A target for Wednesday earlier this year according to the Times, Adarabioyo has struggled to break into Pep Guardiola's first team plans at Manchester City. The 20-year-old's only senior appearance this season came in the EFL Cup two months ago, although he has been keeping himself fresh in City's Under-23s. A loan move could be the next logical step for Adarabioyo, and Wednesday would perhaps be a good fit.