Just a week on from throwing away three points, after leading from an 83rd minute goal at Blackburn Rovers, the Owls were guilty of tossing away victory again against Swansea City at Hillsborough after a 2-2 draw.
Garry Monk’s side missed chance after chance before Andre Ayew netted for the Swans against the run of play.
But goals from substitute Fernando Forestieri and Morgan Fox looked to have secured the Owls a deserved win.
Yet deep into stoppage-time, Ben Wilmot headed in a Swans corner to earn a share of the spoils and leave Wednesday with just six points from their last five games.
The Owls kicked off with the joint best defensive home record – along with Leeds United, they had conceded just three goals on their own patch - in the Championship.
Only Jordan Hugill and Tom Cairney had scored for a visiting team to Hillsborough this season in the Championship.
Hugill netted twice for QPR in the Owls’ only home defeat, and Cairney netted in a 1-1 draw with Fulham.
But German centre-half Julian Borner – a free transfer in the summer – has been integral to Wednesday’s miserly defence.
But with the centre-half missing through illness, Owls captain Tom Lees made his first start under Monk. Lees had not played since August due to a hamstring injury.
That was one of four changes made by Monk, midfielder Sam Hutchinson also out, while Joey Pelupessy and Adam Reach dropped to the bench. That meant recalls for Barry Bannan, Kieran Lee and Atdhe Nuhiu after last week’s loss at Blackburn Rovers.
And the Owls were unlucky not to take an early lead, when Kadeem Harris’s corner picked out Jacob Murphy, but his strike was blocked on the line by goalkeeper Freddie Woodman.
This was arguably Monk’s most attacking line-up in his 10th Championship game in charge – with two centre-forwards, two direct wingers and no holding midfielder – and Nuhiu was next to go close, floating his shot over the crossbar.
Woodman denied Fletcher from close-range, while Nuhiu’s header was deflected over.
All that was missing from the hosts’ high-tempo start was a goal.
After 13 corners at Ewood Park, without reward, the Owls had clearly been working on set-pieces and another corner caused panic, this time Nuhiu going close, before Fletcher’s header bounced to safety off the post.
But, it was the visitors who opened the scoring against the run of play.
Goalkeeper Keiren Westwood dropped a corner, and in the panic, Ayew nipped in front of Fox to prod the ball into his own net.
The goal certainly knocked Wednesday out of their stride, Bannan’s long-range strike, just before half-time, arrowed straight into the arms of a relieved Woodman.
Chances kept coming for the Owls after the break, Fletcher’s cross poked wide by Murphy.
Nuhiu’s unmarked header from eight yards out drifted wide, Fletcher’s header was saved by Woodman, before Murphy smashed the rebound against the post.
Ayew should have made it 2-0, but headed wide when unmarked, before Nathan Dyer’s effort was deflected wide.
If Westwood was at fault for the goal, he made amends with a stunning save to keep out Connor Roberts’s effort.
And moments later the Owls finally netted, with two substitutes playing key roles.
Reach’s long-range strike was parried by Woodman, Lee pulled the goal across goal, and Forestieri – on as a replacement for Nuhiu - arrived to fire home.
Fletcher saw a ‘goal’ disallowed for offside, before the Owls grabbed a stoppage-time goal.
Another Owls corner caused mayhem in the Swans defence, and Fox blasted in the loose ball.
But the cheers had barely subsided before the Welsh visitors grabbed a equaliser.
Westwood pulled off a stunning close-range save to thwart Sam Surridge, but from the resulting corner, Ben Wilmot powered in a header.