United's women fell to a 2-0 defeat away at London Bees as Carla Ward's side failed to make it three wins on the bounce after a good run of form.
In a below par performance, United's best chance came in the opening minutes when Jade Pennock hit the bar, but goals after the break from Ruesha Littlejohn and Nicola Gibson sealed the three points for the hosts.
Ward named an unchanged side to the one that beat Leicester City last week and it nearly had the desired effect when Pennock cut in from the right and smashed the crossbar from the edge of the area.
An even first half saw both sides create chances, Chloe Dixon having a couple of half chances while former England international Rachel Unitt hit the bar herself with a free-kick down the other end.
Goalkeeper Alex Brooks denied Ruesha Littlejohn, the first of several good saves from the United keeper, before the Blades were dealt a blow before half-time when Bex Rayner had to go off injured.
United didn't come out for the second half in the same way they ended the first and fell behind 10 minutes after the break when Littlejohn beat the offside trap and slotted home from Katie Wilkinson's neat little through ball.
The goal turned the tide of the match and United never recovered as the hosts went chasing a second.
Brooks had to be on form several times to deny Littlejohn before Gibson found the net from close range with 10 minutes to go to end United's hopes of a result.
Bees could have added more had it not been for Brooks' good form in goal while Sophie Barker came closes to a consolation when she fired narrowly over in stoppage time.
Blades: Brooks, H. Barker, Fletcher, Cox, Gilliatt, Pennock, Tierney, S. Barker, Merrick (Michalska 59), Rayner (Ford 43), Dixon (Kemp 71).
Unused: Davies, Jones, Hartley, Ibbotson.