It was such a blooper that not everyone in St Andrew’s saw it happen – Alex Neil and Paul Gallagher both confessed post-match that they hadn’t, so too Garry Monk.
Half of the press box didn’t, nor did Maikel Kieftenbeld the man who benefited the most from Rudd’s clanger.
Kieftenbeld had already turned round to get himself back in position after hitting a shot from 40 yards.
Tamely it bounced twice in the Preston penalty box and then passed through Rudd’s legs as the goalkeeper took his eye off the ball.
Was it even a shot from the Birmingham midfielder or an over-hit through ball?
Many had turned away by the time it reached Rudd, this not a case of folk trotting out the Wenger time-honoured ‘I didn’t see it’ excuse.
PNE boss Neil said: “The ball went over the defender and I turned, ready to follow the ball up the pitch.
“Then I heard their fans celebrating.”
Neil’s Blues counterpart and one-time team-mate Monk had done similar.
“I walked away after Kiefer’s pass, cursing under my breath an over-hit pass,” said Monk.
“I turned away from it, heard the crowd’s response and it was in the net.”
Whether you watched it in real time or later on television and social media, there was no denying that Rudd’s error was a game-changer.
It was a gift of an opening goal at the start of the second half following a tepid first 45 minutes in which North End had comfortably dealt with what the hosts had to offer.
The longer the game had gone on, the more patched-up PNE would have fancied their chances of getting a result.
But there was no coming back from this, it knocked the belief out of Neil’s men and the home side scored twice more to clinch a convincing win.
For the record, goals two and three were good finishes from Jacques Maghoma and Che Adams.
Rudd will have wanted to dig a hole and crawl in following the first goal.
In fact much of North End’s second-half display could have been thrown into that same hole.
Heads went down that bit too easily and belief was lost, the 3-0 scoreline their joint heaviest this term.
Few players came out of this one smelling of roses, the afternoon as grim for Preston as the Midlands weather on the day the calender flipped over to December.
Although there is reluctance by Neil to use the lengthy injury list as an excuse, it surely can be used as mitigation?
This was the game when injuries came home to roost.
You can get away with three or four injuries to key men, even five.
But to have eight players out proved a step too far.
Technically, it was seven missing from action.
Ben Davies was back on the bench after hamstring trouble but Neil admitted that it was unlikely he would have thought about using him.
The latest to be ruled out were Tom Clarke and Ben Pearson.
They were badly missed, skipper Clarke for his experience at the back and Pearson for his drive from midfield.
On top of the absences in the attacking areas, that of Daniel Johnson, Sean Maguire, Callum Robinson, Josh Harrop and Billy Bodin, Saturday was a step too far for the Lilywhites.
With resources limited, Preston’s approach to this one was to stay in the game for as long as they could and see if something came their way as the clock ticked on.
The first-half went to plan in that they didn’t concede and had their best chance of the game in an overhead kick from Louis Moult.
Events moments after the break put a new complexion on the game and Birmimgham took full advantage of the good fortune they were handed.
Darnell Fisher and Ryan Ledson came in for Clarke and Pearson, the bench featuring academy product Jack Baxter for the first time.
Parts of the team had the look of one you might field in the early rounds of the League Cup – not quite a second string but with elements of it.
You could include Jordan Storey in that group but for me he was PNE’s best player on the day.
The centre-back had an awkward customer in Lukas Jutkiewicz to handle and did his job well enough.
Storey tired towards the end as the defence got stretched but otherwise he can look back on this game with some satisfaction.
Rudd will obviously do the opposite and it must be hoped that events in the second city don’t knock his confidence too much.
He got back on the horse with a very good double save to deny Gary Gardner and then Jutkiewicz.
With Neil seeking some continuity between the posts, his keeper selection for the trip to Nottingham Forest will be interesting.
He stuck with Rudd for a couple more games after his error against Bolton earlier in the campaign and might be tempted to do similar.
The first half on Saturday had been pretty forgettable, aside from Moult’s overhead effort which keeper Lee Camp had to tip over.
Rudd’s howler came barely 60 second after the re-start, a headed clearance from Tom Barkhuizen picked-up 40 yards out by KIEFTENBELD.
His swinger of an effort travelled over the North End defence, bounced Rudd’s way and unfortunately travelled through his legs.
Birmingham’s second goal should have been defended a lot better.
MAGHOMA’S first touch to control Maxime Colin’s cross saw the ball rocket into the air off his chest.
But he had the time to take it down a second time on his chest, turn and fire a low shot across Rudd.
When ADAMS sprinted to meet Kieftenbeld’s long ball, cut inside and find the far corner, it was game over from North End’s point of view – it probably had been since the 46th minute when the fight was knocked out of them.