Nigel Clough conceded he was 'bitterly disappointed' with United's 2-0 defeat against Gillingham at Priestfield on Saturday.
The Blades boss admitted he would have settled for a point from a scrappy encounter in Kent, but was angered at how United gave the game away in the latter stages.
Clough reflected: "We are bitterly disappointed with the result. I thought we played well at times in the first-half, but it looked like the game had 0-0 written all over it.
"Then in the 86th minute Mark Howard has a rush of blood, following a poor kick initially and that proves decisive.
"We didn't create an awful lot, but neither did Gillingham. It was a difficult surface and both sides cancelled each other out.
"But we failed to make the most of getting ourselves into some very good situations and that is particularly frustrating.
"It was a tough afternoon, so we would have taken a point in the circumstances and moved on to Tuesday night against Colchester United, but you certainly don't lose the game in the manner we did.
The Gaffer added: "Our final ball was poor, especially when you look at the quality we had out there. Our decision making in key areas wasn't up to standard either and we should have come in at half-time in front after controlling much of the opening 45 minutes.
"We should have had a goal or two to show for our efforts but we haven't got that belief at the moment.
"We played too many aimless balls forward throughout the game. Both teams wiped each other out in midfield, so we needed to be brave and exploit the space down the flanks, but neither of our full-backs contributed anything positive in forward areas.
"We want to win every game, we know though that is unlikely so what you have to do in scrappy games is not lose, like we did last season, but at the moment individual errors are proving very costly."