The Owls produced a controlling display against in-form Blackburn and struck at the last to earn all three points.
Substitute Claude Dielna – only on the pitch for one minute – hit a long ranger that flew in with the aid of a deflection to seal a dramatic win.
It was no more than Wednesday deserved as in terms of ball retention they emerged on top and proved worthy winners overall.
The goal at the death matched the one at the start as Kieran Lee scored his first of the season early in the contest but Alex Baptiste promptly levelled for the hosts.
And just as it seemed the game was heading for a stalemate, Dielna suddenly settled matters with a stunning finish in front of the travelling hoards.
They saw the perfect start too as their team hit the front inside three minutes.
Stevie May took a long ball over the top from Liam Palmer into his stride and the Scot’s effort was saved by Jason Steele but Lee stabbed home the rebound.
Wednesday went on to dominate only to be stung by a counter attack on 16 minutes.
The hosts could count themselves fortunate too as they profited from a deflection off Jeremy Helan before the ball eventually landed to Baptiste, whose skewed shot found a way past Keiren Westwood.
The Owls were undaunted and went close through May, who again burst free on goal but this time Steele made the save.
Wednesday then suffered a blow on the half-hour when Lewis McGugan clashed heads with Lee Williamson and received treatment for a good five minutes before being stretchered off.
And it was almost a double setback as moments later Jordan Rhodes got a strong connection on Craig Conway’s cross but the hitman’s header struck the post.
Westwood saved well at the near post from Shane Duffy four minutes into the second half and, just like the first, the Owls went on to boss possession.
Blackburn struggled to get out of their own half, prompting Gary Bowyer to make a double substitution on 66 minutes.
And the move certainly breathed new life into the home side – Ryan Tunnicliffe unleased a piledriver that Westwood tipped acrobatically over the crossbar.
Then, deep into stoppage time and out of nowhere, Dielna marked his introduction with a blistering hit from 25 yards that gave Wednesday back to back wins following last Saturday’s home triumph over Wigan.
Blackburn: Steele, Hanley, Rhodes, Marshall, Olsson, Baptiste, Williamson (Tunnicliffe 66), Duffy, Evans, Conway (Dunne 83), Gestede (Brown 66)
Owls: Westwood, Palmer, Loovens, Lees, Helan, Maguire, Lee, McGugan (Mattock 34), Drenthe (Lavery 76), Nuhiu (Dielna 90), May