A late goal from substitute Jacob Murphy looked to have sent Wednesday on the road to victory only for a late, late double Blackburn salvo to turn the game on its head.
Tosin Adarabioyo equalised with six minutes left on the clock and John Buckley, also on from the bench, struck a fortuitous winner in added time.
It was harsh on the Owls, who stuck to Garry Monk’s gameplan to the letter only to be undone right at the last.
Prior to the drama in the closing stages, the contest appeared to be heading for a goalless draw. Chances were few and when they did come, goalkeepers Keiren Westwood and Christian Walton had the upper hand.
Rovers showed first when Sam Gallagher forced Westwood into a diving save before Kadeem Harris did likewise to Walton at the other end.
Wednesday won a flurry of corners without troubling the hosts’ defence but that changed on the half-hour mark when the deadlock was almost broken.
Joey Pelupessy sent an accurate free kick to the back post and Dominic Iorfa glanced goalwards but Adarabioyo hoofed off the line.
Steven Fletcher volleyed wide and then headed over as the Owls applied the pressure ahead of half time but the whistle came and went without any action of note.
Five minutes into the second period, though, Blackburn fashioned two clear cut openings from which they should have taken the lead.
First Julian Börner showed perfect timing to block an Adam Armstrong shot from close range, then Westwood dashed off his line to keep the onrushing Lewis Travis at bay.
The Owls introduced Fernando Forestieri to provide a spark but Rovers were next to threaten, with Westwood palming Armstrong’s drive to safety.
The Owls’ keeper tipped a Joe Rothwell header over the crossbar moments later before Wednesday countered and Walton did well to get a strong hand on Harris’ low hit.
Then, on 84 minutes, the Owls struck first blood. Morgan Fox crossed to Fletcher, whose hooked half volley hit the underside of the bar, landing nicely for Murphy to nod home.
But Rovers regrouped and had the final word, striking two last-gasp blows to devastate the travelling hordes.
With two minutes to go, Adarabioyo looped a header over Westwood and in, seemingly snatching a point for Tony Mowbray’s men.
But deep into stoppage time, Buckley benefited from a huge slice of fortune as his low shot took a wicked deflection off Sam Hutchinson to wrongfoot Westwood and give Rovers the advantage.
Incredibly, the Owls went within a lick of paint of salvaging a draw with moments remaining when Forestieri unleashed a fierce daisycutter from distance that smashed against the post and Walton saved superbly from Hutchinson to preserve the victory.
Wednesday: Westwood, Palmer, Iorfa, Börner, Fox, Reach (Murphy 70), Hutchinson, Pelupessy (Forestieri 61), Lee, Harris (Nuhiu 77), Fletcher