Two late goals from the Owls secured the most unlikely of points at Bramall Lane as Wednesday came from 2-0 down to draw 2-2.
Stephen Quinn and Ched Evans put United two goals to the good in the first half but Chris O'Grady and Gary Madine hit back late in the clash to win a memorable point in S2.
In typical derby day fashion, the choruses from both sets of supporters were loud, making for a lively atmosphere in S2.
There was a frantic pace about the early exchanges as James O'Connor almost picked out Madine inside the Blades' six yard box but Matt Lowton made a key interception at a vital moment.
As Wednesday began to settle into their stride, Ben Marshall's long throw was causing United problems but it was the Blades who drew first blood on 11 minutes.
Evans cut inside from the right and his deflected shot came back off the upright for Quinn to knock home the rebound.
Then came a key moment in the game as Madine rose high in the Blades' area to head on target with Simonsen parrying into path of O'Grady, but the United keeper made an incredible save on the deck to deny the striker from close range.
Straight from that incident, the home side went up the other end and doubled their advantage as Evans planted a fine near-post header beyond Stephen Bywater.
Wednesday were creating chances and looking likely to get back in the game as Jose Semedo delivered a dangerous ball in the area but the unmarked O'Connor saw his header rise over the bar.
Simenson then produced another good save from Marshall, as the winger cut inside from the left and thumped his effort on target, but the United keeper tipped the ball onto the crossbar and out for a corner.
As the Owls looked to up the ante before the break, Danny Batth had a chance to halve the arrears but headed wide from Marshall's corner and Wednesday went in at half time ruing missed opportunities at 2-0 down.
Gary Megson sent Jermaine Johnson into the attack after the interval in place of O'Connor.
Marshall came close from a long range free kick but chances were few a far between in the early moments of the second period.
With 66 minutes on the clock, Madine had a sight at goal when Marshall delivered another testing cross from the left but the striker headed inches over the crossbar.
As the hosts looked to put the game beyond doubt, Rob Jones did well to intercept Matt Phillips' cross and clear the danger.
The Owls were given a lifeline with seven minutes to go when O'Grady headed past Simonsen from close range to set up a tense finish at Bramall Lane.
Marshall's floated delivery found Jones at the back stick who headed back into the danger zone for O'Grady to apply the finishing touch.
And that lifeline was duly taken when Madine rose high in the area to head beyond Simonsen with Kevin McDonald perhaps getting the final touch.
And Wednesday almost won it at the death when Jones headed on target but Simonsen made a simple stop.
Nevertheless, it was the Wednesday fans who were left the happiest at full time after an incredible fight back at the Lane.
Blades: Simonsen, Lowton, Montgomery, Evans (Porter 84), Williamson (Phillips 68), Collins, Cresswell, Maguire, McDonald, Quinn, Williams
Substitutes: Jean-Francois, Long, Clarke
Owls: Bywater, Buxton, Batth, Jones, R Johnson, Marshall, Semedo, O'Connor (J Johnson 46), Lines, Madine, O'Grady
Substitutes: O'Donnell, Bennett, Prutton, Palmer