Derby referee Neil Swarbrick earned himself a place in derby legend this afternoon with a decision that could all-too easily cost the Canaries their place in the Championship next season.
With just two games left, City are now a point adrift of Barnsley, who still have that game in hand.
If results fail to go Norwich's way in both mid-week and next Saturday and they, in turn, fail to beat Reading at Carrow Road the following Monday night, the Norfolk side could be down before they ever step foot into The Valley for that final game of the season.
Little wonder that Gunn displayed a controlled fury afterwards as the game turned on the hour-mark as Kevin Lisbie span clear and David Marshall advanced.
As to what followed, Gunn deferred to the opinion of his opposite number, Jim Magilton.
“I don't want to speak about him,” vowed Gunn, after watching David Mooney's early opener be wiped out by Alan Quinn's leveller eight minutes later.
“I'd rather speak about what Jim Magilton said to me. That he didn't think it was a penalty.
“And Kevin Lisbie walking off the pitch and saying that he wasn't going to get the ball; that his momentum took him forward; that he wasn't even facing the goal; that there was minimal contact.
“But the referee decided to give it from where he was – from the position he took up on the half-way line.”
The Lancashire official took forever to make the decision; he looked to his far assistant for guidance and got none. With the North Stand in full and vocal appeal, he pointed to the pot and up stepped Giovani dos Santos to bang a very large nail in Norwich's Championship coffin.
Whether they can rise from the dead once more will first depend on how Barnsley fare at the Ricoh on Tuesday night when they play their game in hand. Victory at a off-to-the-beach Coventry City will leave Norwich staring straight at the abyss.
“It's 'if',” said a defiant City boss. “We'll just have to wait and see what happens next week.
“We've got a game next Monday night and we can't do anything about what happens next Saturday,” said Gunn, not about to claim that his side deserved all three points – one might have been a fairer share of the spoils.
“The team showed a commitment there; they battled right to the end; the fans were right behind us. And their response to the players and to me afterwards was magnificent, so we've got to hope that come Monday evening when we play Reading we've still got an opportunity to go out and play in front of them.
“And if we can get the points, we can keep ourselves in the hunt on May 3.”
If City fans wanted a derby game that lived its life on a knife-edge then the first-half certainly gave them that.
It was all classic, border warfare fare with a tense and techy under-current that prompted two bookings before the break – and at least as many finger-jabs in the face.
It also produced two goals. The first – to the visitors glee – fell to Mooney with a perfectly-executed, stooping header that tucked a deep, 15th minute Sammy Clingan free-kick inside Richard Wright's left-hand post from off the penalty spot.
At which point you could hear the proverbial pin drop among the Suffolk faithful as Magilton's managerial reign in IP1 hung by a thread.
The prospect of the Irishman 'being sacked in the morning…' lasted little more than eight minutes before Quinn dished up a decent leveller.
Driving deep and direct into the heart of the Canary box, the Town midfielder found a willing accomplice in Pablo Counago who teed him around a helpless Jason Shackell to drill the ball inside the far post.
Given it needed a fabulous last-gasp tackle from Ryan Bertrand to deny Giovani dos Santos before the break as Darel Russell forced Wright into a fine, finger-tip save with a dipping 25-yarder, 1-1 was a fair reflection of the contest at the interval. Not that did anything to still the beating, anxious hearts either side of the Waveney.
By the end of the contest, of course, those same nerves would have been in shreds as two goals in added-on time, kept events on a knife-edge to the very final whistle.
By then, however, the real damage had be done as Kevin Lisbie found himself free in the inside-left channel; free enough that is to nick the ball away from the stranded Marshall and take a timely tumble over the Norwich keeper.
The referee took an eternity to blow, but blow he did. And from the subsequent spot-kick Giovani made no mistake.
Substitute Cody McDonald would do his best only to send a hanging header over as Mooney lurked before Jon Stead all-but wrapped up events as he took full advantage of a static City defence to tuck away his 90th minute chance with ill-timed aplomb.
Whether he was offside or not wasn't the issue; City stood still as they appealed. And the whistle never came.
Two minutes later and Clingan pulled one back from the penalty spot after a push on Alan Lee. But it was all too little, too late. Time had run out on City.
Whether time has run out on City full stop will be for the next two games to decide. Six points and they still have a chance; four possibly. Anything less and it could, indeed, be a weekend away in Yeovil.