Atdhe Nuhiu’s early header was cancelled out by a Jonny Williams strike as the Owls were held to a draw by Ipswich at Hillsborough.
Nuhiu struck just five minutes into the clash only for substitute Williams to set up a tense final half hour with his strike mere moments after entering the fray.
The Owls saw two goals chalked off after a foul and an offside as the win slipped from their grasp.
Nuhiu’s early goal had been enough to see the Owls carry a slender lead into the second half.
The towering forward met a Jacques Maghoma corner at the near post six yards out and flicked a header which Dean Gerken could not keep out from under his bar with just five minutes on the clock.
The corner came about as Chris Maguire fired the first warning shot for the Owls, drawing a fine save from Gerken with a long range effort.
Ipswich took 15 minutes to register their first real attempt on goal but a scuffed shot from David McGoldrick proved easy to claim for Keiren Westwood.
The Owls had a goal disallowed on 23 minutes. Kamil Zayatte turned in a header after a Glenn Loovens effort from a corner was saved but referee Darren Bond pulled play back for a foul.
There was a nervy moment at the other end when Westwood appeared to carry the ball out his area in scooping up but Bond was unmoved.
Zayatte – who’s naming in the starting XI was the only change for the Owls – lasted 39 minutes before pulling up with an apparent hamstring problem which ended his night. Claude Dielna came on in his place.
As the first half drew to a close, Westwood had to be alert to deny a low fizzing shot from Luke Hyam.
And Ipswich really should have drawn level. Daryl Murphy met a Tyrone Mings cross but headed wide across goal.
The Owls could have been two up early after the break as they looked to stretch their league.
Nuhiu met a free kick from Maghoma and lifted the ball over Gerken only for the referee’s assistant to raise his flag.
Before Williams equalised, Maguire could have doubled their advantage but thumped a volley wide.
And then the sub struck. Williams collected the ball just inside the box and drilled through a crowd of players into the far corner, cancelling out Atdhe Nuhiu’s fifth minute opener for Wednesday.
And as the final ten minutes approached, Stevie May could have put them back in from but headed a Maghoma centre narrowly wide.
Ipswich really should have gone in front seven minutes from time when Christoph Berra rose to meet a free kick from substitute Paul Anderson but powered his effort over the bar.
Wednesday: Westwood, Buxton, Zayatte (Dielna 39), Loovens, Mattock, Maguire (Helan 72), Palmer, Semedo, Maghoma, May, Nuhiu. Not used: Kirkland, Coke, Drenthe, Hope, Madine
Ipswich: Gerken, Parr, Chambers, Berra, Mings, Skuse, Bishop (Williams 58), Hyam, Murphy, Sammon (Anderson 75), McGoldrick. Not used: Bialkowski, Smith, Bajner, Bru, Tabb.
Referee: Darren Bond