A maiden goal from new cult hero Julian Borner seemed to be steering Wednesday to an impressive win at Cardiff but a late response from substitute Lee Tomlin denied the visitors three points.
A horrible night punctuated by driving rain was going the way of the Owls, who turned in a composed first half display that saw them head down the tunnel at the interval in the box seat through Borner.
And had Kadeem Harris’ free kick nestled in the top corner instead of cannoning off the crossbar, the win would in all likelihood have been Wednesday’s.
From the first whistle, the Owls were on the front foot, asking consistent questions of the Bluebirds’ backline.
For their part, Cardiff gave deputy keeper Cameron Dawson – a late replacement for Keiren Westwood – few concerns.
And at the other end Steven Fletcher and Harris sent early sighters before the latter set up Borner for a deserved opener on 19 minutes.
The former Cardiff man struck a sweet hit from the edge of the area that might have crept in but any doubt was extinguished by Borner, who diverted past the wrong-footed Neil Etheridge.
Borner then glanced a Barry Bannan set piece over the crossbar before Etheridge dived to keep out a curling Fletcher shot from distance.
Pressure from the Owls prompted the hosts to make a change ahead of the interval as crowd favourite Danny Ward was introduced from the bench.
But the move changed little of a largely one-sided first half that came within a whisker of ending with more trouble for City.
Harris lined up a free kick 25 yards from goal and his strike was true, only for the ball to crash against the angle of the woodwork.
The Owls continued in the same manner after the break as Cardiff, so convincing on home soil this term, struggled to get a grip on the game.
Bannan was pulling the midfield strings, with one ball over the top for Adam Reach particularly sublime and only a last-ditch challenge from Aden Flint diverted the danger.
The Bluebirds did start to creep back into proceedings around the hour-mark and Dawson was called into action for the first time, palming a Robert Glatzel header round the post.
Wednesday sent on Atdhe Nuhiu to stem the tide but Cardiff had the upper hand heading into the closing stages.
Josh Murphy went agonisingly close with a looping cross that evaded three onrushing Bluebirds and the same player miskicked from 12 yards from an inviting Ward feed.
But Cardiff’s time would come three minutes from the end when Tomlin lined up a free kick just outside the ‘D’ and executed a near perfect delivery that rescued a point.
And it might have been more in stoppage time but for a super Dawson save low at his near post that denied Gavin Whyte what would have been an unlikely winner.
Wednesday: Dawson, Palmer, Iorfa, Borner, Fox, Reach, Bannan (Nuhiu 73), Hutchinson, Luongo, Harris (Murphy 79), Fletcher