Instead they defied the odds and turned the tide under the Deepdale lights to earn a dramatic point.
A second-half show which thrilled the PNE faithful and left a sizeable Blades support crying into their greasy chip butties, saw them turn a 2-0 deficit into a 2-2 draw.
It was done with 10 men too, Andrew Hughes having ben sent-off before half-time.
Several things combined to spark North End’s fight back which maintained their unbeaten league run under Ryan Lowe’s leadership.
Most importantly, there was a clear belief within the PNE camp that something could be salvaged.
Lowe’s three substitutions worked well, the first two Greg Cunningham and Joe Rafferty, designed to stabilise things at the back,
The third man off the bench was Ched Evans who gave his old club a wretched 25 minutes and played a big part in both Lilywhites goals.
Evans wasn’t quite the star act, that mantle taken by Alan Browne who was quite superb.
Browne drove Preston on throughout the second half and scored the goal which brought them back into the game.
Then the skipper had a hand in the equaliser, playing in Evans to set-up Emil Riis for the 89th minute goal.
There have been games previously when North End battled their way back into a game in such a fashion.
Brentford away last season when they roared back from 2-0 behind to win 4-2, was the most recent.
But Tuesday night’s effort seemed that bit more against the odds, the point welcome but so unexpected.
They’d struggled to contain United’s passing and movement in the first half, conceding the opening goal in the aftermath of a set piece.
When Hughes and Rhian Brewster went to ground in the box seven minutes before the interval, Hughes was shown a red card.
The defender had only just set foot in the tunnel when Billy Sharp banged home the penalty to make it 2-0.
Operation Fight Back started over the half-time tea in the home dressing room and how the direction of travel changed in the second half - with the occasional scare.
This was no throwing the kitchen sink job, with a big defender chucked up front to cause a distraction.
North End were measured, they continued to pass the ball when possible.
After Browne’s goal halved the deficit, they didn’t get overexcited and chase it.
The equaliser had its origins on the half-way line, the ball worked forward, then down the sides, played across goal and delivered into the net by Riis who haunted United for a second time this season.
His 95th minute equaliser in the reverse fixture four months earned PNE a point at Bramall. Riis wasn’t quite so late this time but it was no less dramatic.
North End had been largely on the back foot in the first half, Tom Barkhuizen in an unfamiliar left wing-back role and Scott Sinclair starting for the first time since Blackpool away.
The evening’s opener in the 17th minute came after Daniel Iversen had done well to push out John Egan’s far post header.
Jayden Bogle was first to the loose ball on the edge of the box, driving home a low shot.
Hughes’ red card bordered on the harsh even when accepting it was a penalty.
After Sharp had beaten Iversen from the spot, Lowe hooked Sinclair and put Cunningham in defence.
Rafferty took the place of Brad Potts at half-time and as the second half went on, PNE switched to a 4-3-2.
In the 71st minute, Evans collected a throw in and knocked a ball for Daniel Johnson to chase down the left hand side of the box.
He rolled a pass back into the path of Browne who steered a shot into the far bottom corner.
Parity came when Patrick Bauer won a header on half-way, Browne collecting the second ball and driving forward.
He slipped a pass out to his right to Evans, the striker threading a great ball along the ground to the far post where Riis slid in to finish.
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