Cardiff City 1 Sheffield Wednesday 1 - Lee Tomlin's controversial late strike breaks the Owls' hearts
Yet another refereeing howler cost the Owls a first ever win at the Cardiff City Stadium.
Wednesday looked on course to record back-to-back Championship victories and move up to second in the table courtesy of Julian Börner's maiden goal in English football.
But substitute Lee Tomlin rescued a point for the Bluebirds, curling a delightful free-kick home in the 87th minute to break the Owls' hearts.
There was plenty of controversy surrounding the equaliser as Tomlin appeared to foul Massimo Luongo, not the other way round.
But referee Keith Stroud, who incensed both teams with his questionable officiating, awarded the free-kick the home side's way. Giant Cardiff centre-back Aden Flint then stood between the wall and the goalkeeper in an offside position as Tomlin took the free-kick but nothing was given and the goal stood.
This is the third match running a refereeing decision has gone against Wednesday. They were denied a blatant penalty at Hull City and had a goal wrongly chalked off versus Wigan Athletic before the international break.
The result was harsh on Garry Monk's side, who should have been out of sight after dominating the first half.
But they failed to take their chances and the Bluebirds made them pay for their profligacy. Indeed, Cardiff could have snatched maximum points at the death had Cameron Dawson, drafted in as a late replacement for Keiren Westwood, who suffered an ankle injury in the warm up, not pulled off a stunning save to deny Gavin Whyte as Neil Warnock's men pushed for a winner.
On a wet, miserable evening, Wednesday had the first chance of note. Stand-in skipper Barry Bannan poked the ball to Steven Fletcher on the edge of the penalty area but the striker's tame left foot drive was easily saved by Neil Etheridge.
Kadeem Harris, who left the Bluebirds in the summer after making 79 appearances in a seven-and-a-half-year spell, fired high over the top from an acute angle as the Owls continued to make all the early running.
As expected, former Swansea captain and manager Monk received plenty of stick from the Cardiff fans in the early stages. Monk, 40, played in four South Wales derbies for Swansea before going on to manage the Swans to their first derby-day win in the Premier League against Cardiff in his first match as boss.
But it was first blood to Monk in the 19th minute when Börner cleverly flicked the Owls in front. Fletcher fed Harris, who cut inside on to his right foot and unleashed a rasping shot which was diverted in by Börner past a helpless Etheridge.
It was a poacher's finish from Börner and his first goal since joining Wednesday on a free transfer from Arminia Bielefeld.
Börner could have doubled Wednesday's lead just after the hour mark but nodded over Bannan's free-kick after a clumsy foul by Lee Peltier on the lively Harris.
Moments later, Fletcher's left foot curler from long range was punched to safety after great approach play by Massimo Luongo and Sam Hutchinson as Monk's side pressed hard for a second.
Cardiff were completely outfought and outplayed in the first period and Warnock made a tactical alteration in the 34th minute, taking off Leandro Bacuna and throwing on in-form forward Danny Ward.
There were some strange decisions from referee Stroud but he rightly yellow carded Hutchinson after he unceremoniously brought down Nathaniel Mendez-Laing near the half-way line.
Harris, a constant thorn in the Bluebirds side, almost bagged a second. His dipping, curling right foot free kick struck Etheridge's crossbar and bounced clear.
As the rain continued to pour down, Cardiff finally fashioned a chance as Robert Glatzel nodded Joe Ralls' delivery over.
Dawson was not forced into a save as he was expertly protected by Dominic Iorfa and the irrepressible Börner.
The visitors were good value for their lead and Etheridge was equal to Fletcher's effort inside the six-yard box after yet another incisive move.
There was no let up from the Owls after the break as Luongo burst into the box only to see a shot well blocked by Bluebirds skipper Sean Morrison.
Dawson produced a good save just after the hour mark to keep out Glatzel's header after a whipped free kick into the area.
Cardiff, relegated from the Premier League last season, lacked ideas for long periods in the final third but they woke from their slumber in the final quarter of the contest. Joe Ralls blasted a free-kick high over the top before Ward was thwarted by Dawson.
As the half wore on, Wednesday were pinned back deep in their own half and had to soak up an aerial barrage from the hosts.
They could have put the contest beyond Cardiff when Luongo played Bannan in but the little Scot fired straight at Etheridge when well-placed.
With 13 minutes remaining, the Bluebirds went agonisingly close to levelling things up when Josh Murphy, the twin brother of Owls loanee Jacob, drove to the byline and saw his cross take a wicked deflection off Palmer and nearly creep in at the far post.
Left-back Morgan Fox, handed his first league start since the end of August, produced an immaculate challenge to stop Whyte from racing clear.
But Cardiff’s relentless pressure eventually told as Tomlin restored parity in contentious circumstances to frustrate Wednesday.
Cardiff: Etheridge; Peltier, Morrison, Flint, Bennett; Bacuna (Ward 34), Pack, Ralls; Mendez-Laing (Whyte 76), Murphy, Glatzel (Tomlin 76). Substitutes: Smithies, Nelson, Paterson, Hoilett.
Owls: Dawson; Palmer, Iorfa, Börner, Fox; Hutchinson, Bannan (Nuhiu 73), Luongo; Reach, Harris (Murphy 79), Fletcher. Substitutes: Pelupessy, Forestieri, Lee, Odubajo, Thorniley.
Referee: Keith Stroud (Hampshire)