Ben Wilmot snatched a point for Swansea City as they kept their unbeaten away record intact in a dramatic finish at Hillsborough.
Andre Ayew’s close-range finish for his sixth goal of the season had given the Swans a 32nd-minute lead in South Yorkshire.
They looked on course for just a second victory in 15 league trips to face Sheffield Wednesday, but were pegged back with 10 minutes to go as Fernando Forestieri finished from inside the six-yard box.
And they looked set to end up with nothing to show for their efforts as Morgan Fox slammed home in stoppage time after the Swans had been unable to deal with a corner.
But with a heartbreaking defeat in prospect, up popped Wilmot to find the bottom corner in front of the 700 travelling Jacks who had made the journey to South Yorkshire.
There had been little sign of the chaotic finish to come in what was an error-strewn encounter, but three goals in the final 10 minutes plus stoppage time put nerves through the shredder.
And any frustration Steve Cooper and his side will feel at dropping points from a winning position, will surely be tempered by yet another late, late show from the Swans.
Cooper had named an unchanged line-up for the third game running but it was the hosts who started on the front foot, with Wilmot making an important clearance after Steven Fletcher had beaten the offside trap.
From the resulting corner Freddie Woodman made an excellent save to deny Jacob Murphy from a well-worked corner routine.
Mike van der Hoorn made a vital header as Atdhe Nuhiu closed in on a Kadeem Harris centre as the pressure continued.
Nuhiu swept an effort over the bar after a loose ball fell for him on the edge of the area.
Swansea could not lift the siege, with Woodman denying Fletcher’s header from a deep corner with Nuhiu sending a follow-up header over via a deflection off Ayew.
Swansea responded, with Ayew getting the benefit of an offside decision to nearly finish a flowing move, only for Liam Palmer to make an important block.
A clever run from Nathan Dyer than caused problems in the Wednesday defence, with Keiren Westwood having to prevent defender Dominic Iorfa putting through his own net.
But the Owls were soon back on the front foot, Fletcher getting above his man to guide a header beyond Woodman only for the ball to hit the post and Swansea to scramble to safety.
And the hosts profligacy was punished when Ayew prodded home from close range after Westwood had been unable to hold a Matt Grimes corner – which Wednesday had conceded when Fox failed to hear his keeper’s call and headed just over his own bar.
It was enough to give the visitors the interval lead, but they were very nearly pegged back early in the second half.
Fletcher got clear down the left and his fantastic cross should have laid on an easy finish for Murphy, but the winger somehow sent the ball wide of the post.
Wednesday continued to waste chances with reckless abandon. Nuhiu headed straight at Woodman from a teasing Harris cross, and Murphy leathered the rebound against the inside of the post with the goal at his mercy.
It was Ayew’s turn to miss a massive chance just after the hour mark, sending a free header wide from Kyle Naughton’s pinpoint centre.
Wilmot was then denied by Westwood as he powerfully met a Grimes corner, before Ayew volleyed at the keeper from Bersant Celina’s scooped pass as the game entered its final 20 minutes.
Westwood again denied Ayew after he cleverly turned from a Grimes ball into the box, but Wednesday levelled with 10 minutes remaining.
It was substitute Adam Reach who did the damage, bursting forward and driving in a low shot that Woodman could only parry, and his fellow sub Forestieri turned in the follow-up ball across the box.
And they looked to have suffered last-gasp heartbreak as Fox kept his cool as the ball dropped to him in the box from a corner,
George Byers had a chance to snatch a point, but a brilliant save from Westwood denied him only for Wilmot to turn in the resulting corner.
Sheffield Wednesday: Keiran Westood, Liam Palmer, Dominic Iorfa, Tom Lees (captain), Morgan Fox; Jacob Murphy (Adam Reach 75), Barry Bannan, Kieran Lee, Kadeem Harris (Jordan Rhodes 83); Steve Fletcher, Atdhe Nuhiu (Fernando Forestieri 66).
Substitutes not used: Cameron Dawson, Joey Pelupessy, Jordan Thorniley, Moses Odubajo.
Swansea City: Freddie Woodman; Kyle Naughton, Mike van der Hoorn, Ben Wilmot, Jake Bidwell; George Byers, Matt Grimes (captain); Nathan Dyer (Connor Roberts 77), Bersant Celina (Jay Fulton 83), Wayne Routledge (Sam Surridge 87); Andre Ayew.
Substitutes not used: Kristoffer Nordfeldt, Ben Cabango, Kristoffer Peterson, Borja Baston.
Attendance: 23,073
Referee: David Webb