The forward cancelled out Sophie Bradley’s opener to turn the game on its head at half time, with Maria Farrugia and Emma Kelly rounding off an emphatic win.
The Black Cats were without captain Keira Ramshaw who was unwell, and the suspended Louise Griffiths for the trip to Yorkshire, with Holly Manders and Megan Beer coming into the starting XI.
And the away side almost took the lead within the first five minutes as Abbey Joice found Farrugia in the box who did well to slip her marker but her shot bounced off the inside of the far post and into the grateful arms of Nina Wilson.
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The Blades were racking up the corners in the early stages which they made count after 22 minutes as Sophie Bradley broke free to head Lucy Watson’s set into the roof of the net.
But the hosts’ lead lasted for less than 90 seconds as Joice played a superb pass out wide to Scarr who held off a challenge to loop the ball over the stranded Wilson into the top corner.
Looking for an instant response, Paul skied over from the edge of the box and then Moan reacted quickly to deny Courtney Sweetman-Kirk with her feet on the goal line.
Five minutes before the break, Sunderland made it two – Farrugia won the ball in midfield and played in Scarr who ran behind the defence and slotted low into the corner.
Sheffield United came back out early for the second half, determined to get back into the game quickly and almost did through Georgia Wilson but her shot dipped over the bar.
Any momentum Neil Redfearn’s team hoped to build was immediately halted as Farrugia broke clear to grab Sunderland’s third. The Malta international collected Neve Herron’s ball over the top and, despite Maddy Cusack’s attempts to stop her, lobbed the onrushing Wilson.
At the other end, Moan was called into action to parry Watson’s header away before the visitors put the game beyond doubt with their fourth.
Youngster Grace Ede was introduced in place of Emily Scarr and made an immediate impact – forcing a good save from Wilson but the ball fell into the path of Kelly who tapped home.
The victory was the least the Black Cats have deserved for their impressive recent performances with results going against them, and mission accomplished for Mel Reay’s young squad who have achieved their target of staying in the second tier.
Sunderland: Moan; Beer, McCatty, Towers, Mullen; Herron, Kelly ©, Joice; Manders (Brown 72’), Farrugia (Blakey 85’), Scarr (Ede 77’).
Subs: Cowling, Boyes, McInnes, Watson, Burt.
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