Goals from Iliam Ndiaye and Oli McBurnie in each half were enough to sink the Lilywhites, as they once again drew a blank at home.
North End sit 15th, with the Blades top of the table, after the game and this is how we rated them...
13. Robbie Brady - 6
Has been struggling to find the quality in his final balls of late and struggled to get past his man and deliver, though as with Johnson, the game was being taken away from North End. Photo: CameraSport - Rich Linley
14. Ched Evans - 5
Just didn't make any sort of impact after coming off the bench, barely won a header and did not look a threat. Seems to be struggling to get to the pace of the game at the moment. Photo: CameraSport - Rich Linley
15. Sean Maguire - 6
Looked fairly bright after coming off the bench, wanted to get himself about and make up for lost time. Made a smart run in behind before claims for a penalty. Photo: CameraSport - Rich Linley
16. Ryan Ledson - 6
Got less than 10 minutes at the end but at that point United were seeing out the win, a tough spot to come on at. Photo: CameraSport - Rich Linley