The Blades went two ahead with quickfire goals from Sander Berge and Billy Sharp in the first half, with Jack Robinson and the superb Morgan Gibbs-White on target in the second.
Boro got on the scoresheet through Folarin Balogun, after a rare slip from Wes Foderingham, but United were full value for a rousing victory against a serious promotion rival – managed by their old boss Chris Wilder, who was given a good reception on his return to his boyhood club ahead of kick-off.
But who was United’s man of the match? Click through our photo gallery to see our man’s ratings – including a VERY rare perfect 10 …
5. Jack Robinson 9
Did superbly to halt a bit of Boro momentum at the end of the first half, putting in three blocks in quick succession to keep the visitors at bay. Long throw caused Lumley some problems too and he got in the goalscoring act with a striker's finish on his right foot Photo: Zac Goodwin
6. Rhys Norrington-Davies 7
Solid rather than spectacular but coped well with another tricky assignment up against the pacy and talented Isaiah Jones Photo: Andrew Yates
7. Ollie Norwood 8.5
Benefitted from the freedom of midfield after being man-marked so effectively in the return game at the Riverside. Again broke up play so well in midfield and put his foot in where necessary Photo: Andrew Yates
8. Sander Berge 8.5
Got United up and running with a goal from close range after busting a gut to get into the box for Sharp's cross. Linked up so well with Gibbs-White and looked a threat every time he picked up the ball Photo: Isaac Parkin