United's Under 23s had to settle for a frustrating draw despite plenty of pressure in their 1-1 draw at home to Hull City.
Simeon Oure's deft lob after half an hour brought the Blades right back into a game they'd gone behind in early on after a defensive mix-up.
United started the match on the front foot and could have gone ahead when Reece York won a battle with Hull goalkeeper Harrison Foulkes but saw a curling effort cleared off the line by Josh Thacker.
Greaves curled wide soon after thanks to a bit of neat solo play before United gifted the visitors the lead after 15 minutes.
Miscommunication between George Cantrill and Jordan Amissah saw Cantrill nod the ball past the on-rushing goalkeeper, allowing Hull striker Keane Lewis-Potter the simplest of tap-ins to make it 1-0.
Harry Boyes saw a shot blocked as United looked for a response before Oure brought the game level with a neat lobbed finish after the ball fell to him thanks to Jake Bennett's marauding run into the penalty area.
Kyron Gordon replaced debutant Kean Bryan at the break, the new signing getting a solid 45 minutes under his belt and Gordon's first action was to block a goal-bound shot from Salam who had found himself free on the left side of the box.
United pushed and pushed for a winner but on a day where the Blades could have gone top of the league with a win, the goal never came.
Harry Sheppeard saw an effort come back off the post after a lovely ball over the top from captain Jordan Doherty, before both Gordon and York both headed off target with great chances from two consecutive corners.
Substitute Stephen Mallon thought he'd won it in the dying minutes when he converted Sheppeard's cross but the referee blew her whistle for an alleged pull inside the box by fellow substitute David Parkhouse.
Blades: Amissah, Bennett, Bryan (Gordon 46), Doherty, Cantrill, York, Sheppeard, Greaves (Parkhouse 80), Oure, Hallam, Boyes (Mallon 70).
Unused: S. Kelly, Broadbent.