The Owls posted a massive win at Millwall on Tuesday night and inched another step closer to second tier safety.
Miguel Llera cancelled out Jimmy Abdou’s early goal that caught Wednesday cold and substitute Chris Maguire scored his maiden goal for the Owls in stoppage time to seal victory.
Just two points separated the teams in one of the most unpredictable Championships in years, with the capital clash giving the Owls the chance to leapfrog their hosts in the table.
But Wednesday were off to the worst possible start and conceded with barely a minute on the clock.
Chris Taylor advanced down the right flank before cutting inside to feed Abdou, who was left with the simple task of converting at the back post.
The shell-shocked Owls needed a positive response and Lewis Buxton went close with a long range free kick but play was soon back at the other end, when Millwall carved a clear opening in a bid to double their lead on ten minutes.
Rob Hulse was sent scampering in on goal but Chris Kirkland was off his line swiftly to smother at the feet of the veteran striker.
Steve Howard threatened for Wednesday on the half-hour mark with an angled drive saved by David Forde only for the Lions to immediately hit back as erstwhile Owl Mark Beevers glanced narrowly wide from a corner.
With half time looming, though, and the hosts seemingly heading down the tunnel in front, the Owls drew level in the 40th minute.
Seyi Olifinjana won a free kick 30 yards out and up stepped Llera to dispatch a curling drive right into the corner and beyond the reach of the despairing Forde.
The goal was the tonic Wednesday needed and it was they that showed the early intent in the second half - David Prutton saw a bobbling daisycutter cleared off the line by Shane Lowry - before Millwall began to dominate.
Time and again the Londoners poured forward but the final ball was lacking where it mattered.
When they did find that elusive killer pass, Kirkland was on hand to deal with the danger, as he did twice in as many minutes just past the hour.
First Jermaine Easter burst in on goal but the Owls’ keeper was down sharply to parry clear before Taylor tried his luck from 20 yards only to see Kirkland again come to the visitors’ rescue.
Wednesday threw on pace ace Jermaine Johnson to offer more attacking momentum but it was the Lions that continued to look the more likely.
An acrobatic attempt from Sean St Ledger forced another fine save from Kirkland, who proved a source of frustration for Millwall throughout the contest.
And the Owls might have nicked it when Johnson set off on a trademark run that took him past two defenders but the Jamaican’s shot fell just the wrong side of the post.
But they did take all three points when Maguire superbly volleyed home Danny Pugh’s corner right at the last to seal a huge win for Wednesday.
Millwall: Forde, Dunne, Shittu, Hulse (Batt 56), Lowry, Beevers, Taylor, Abdou, Saville (Henry 56), Easter (Keogh 80), St Ledger
Unused substitutes: Taylor, Woolford, J Smith, A Smith
Owls: Kirkland, Buxton, Gardner, Llera, Pugh, Lee, Prutton, Olifinjana, Helan (Maguire 81), Howard, Lita (J Johnson 62)
Unused substitutes: Bywater, Mattock, Taylor, McCabe, Semedo