The two sides played out a stalemate at Kenilworth Road, although the hosts had the better of things and came closest to breaking the deadlock when Harry Cornick rattled the crossbar in the second half.
Here’s how we rated the Blades players ...
Wes Foderingham 4
Had a nervy moment in the first half when he came to punch a throw-in and wiped out Adebayo as well, but the referee - rightly - didn't take any action. Then was almost punished in the second as he tried to play out from the back, was tackled by Adebayo in his own goalmouth and then Cornick rattled the crossbar
George Baldock 5
Enjoyed a good early chance when Norrington-Davies' cross found him at the back post, but he couldn't get his header on target. Later withdrawn just after the half-hour mark after complaining of pain in his right foot
Chris Basham 5
Saw plenty of the ball in the first half but didn't seem to have too many options to use it. Perhaps could have been tighter to Adebayo as he headed over Luton's best chance of the first half, but was solid enough otherwise. Sacrificed at half-time as United introduced Freeman and changed shape
John Egan 5
Booked early in the second half for a foul on Adebayo and was given a difficult time of things by the Luton man all afternoon
Ben Davies 5
Seemed more composed in a back three than a two, when United struggled to stem the flow of chances at times.
Rhys Norrington-Davies 5.5
Booed mercilessly in the second half, probably when the Luton fans remembered he played for them, Norrington-Davies was full of industry down the left wing but couldn't deliver the touch of invention when it was required
Ollie Norwood 5
Neat and tidy on the ball for the most part, despite relentless pressing from the Luton midfield, and did his job off it as well. Noticeable that Freeman took over set-piece duties when he came off the bench
Sander Berge 5
Showed some good moments but not as many as United want or need from their £22m man. A player of his stature, both literally and metophorically, should be able to impose himself on Championship games much more often, and for longer, than we have seen so far
John Fleck 4
Another frustrating afternoon for the Scot as his slow starts to seasons continue.
Oli McBurnie 4
Poleaxed in the sixth minute by Kai Naismith, earning the Luton skipper a deserved early yellow card. Kicked fresh air in frustration after planting a header over the bar when well placed in the second half. Withdrawn for Brewster
Billy Sharp 5
Recalled to the starting XI after two goals in two games coming off the bench, Sharp worked tirelessly for the team as ever but was reduced to feeding off scraps. After McBurnie went off, United kept crossing in the air for Sharp to battle with Luton's giant centre-halves
Jayden Bogle 5
Didn't do an awful lot to justify the calls for him to start games over Baldock, but may soon get the chance anyway depending on how bad the full-back's injury is
Perhaps unfortunate not to start after his goal in midweek, Freeman came on at half-time and was visibly frustrated with himself as he misplaced two passes in a matter of moments out of play. But was bright otherwise as he at least looked to make something happen. Must surely be knocking on the door to start in the league
Rhian Brewster 4
An attempted cross, that fizzed miles over anyone's head in the middle and bulleted out for a throw-in on the far side, rather summed up United's afternoon