A last-minute strike from Jade Pennock sealed United's women's team a huge three points away at league leaders Tottenham Hotspur.
Carla Ward's side had trailed when Jessica Naz opened the scoring shortly after half-time but the Blades showed huge character to comeback through goals from Ebony Salmon and Pennock's late effort.
In truth, it was a three points United deserved despite the points gap in the table. The Blades started on the front foot and had chances to go in at the break in the lead but a combination of wayward finishing and some good goalkeeping from Chloe Morgan kept the scores at 0-0.
Salmon had the first attempt but her effort was over the bar before Danielle Cox tested Morgan with a stinging effort from the edge of the box.
Salmon was causing all kinds of issues with her pace and direct running but more chances came and went as United went in at the break at 0-0.
Bex Rayner tested Morgan straight after the interval and it looked like United had been made to pay when Jess Naz suddenly broke through on goal and slotted the ball beyond Fran Bentley.
But United responded and surprisingly, Bentley was the architect. Her ball from the back found its way to Salmon and the on-loan striker replicated Naz's goal and slotted home calmly past Morgan.
The game became a fairly frantic affair in the final 20 minutes as both sides pushed for a winner without really being able to test either goalkeeper.
The winner came just as the game moved into stoppage time. Rayner's free-kick was lifted into the box and as it found its way through to Pennock, she did the rest and turned the ball into the bottom corner of the net to seal a massive three points.
Blades: Bentley, S. Barker, Pennock, Cox, Rayner, Paul (Tierney 62), Dixon (Sarri 62), H. Barker, Cusack, Hartley, Salmon.
Unused: Davies, Ford.