Nigel Clough was annoyed to see 'a game changing' decision curtail United's eight-match unbeaten run with defeat at Walsall on New Year's Day.
Two second-half goals, including a disputed penalty from Craig Westcarr, saw United, who had taken the lead through Chris Porter, begin 2014 with an undeserved loss.
Speaking afterwards, Clough couldn't hide his frustration at the incident that occurred in the early exchanges of the second-half.
The Blades boss remarked: "It was bitterly disappointing to see the unbeaten run come to an end in the way it did. The decision completely changed the game. We saw nothing for the penalty and not one Walsall player appealed to the referee.
"Our players were absolutely disgusted, it is an old cliché, but given that decision, we should be looking at ten penalties a game."
On the game in general, Clough was encouraged by many aspects of United's performance, but was left ruing a lack of concentration during the build-up to the Saddlers' winning goal.
The Gaffer added: "We started the game fantastically well and thoroughly deserved our goal. We looked comfortable for the remainder of the first-half and could have added to our lead.
"In the second-half we tried to remain positive, but the penalty award was a game changing decision, it certainly gave Walsall a spark, although the second goal was a disappointing one to concede. The runner came from deep and he hasn't been tracked, so that gives us something to address.
"Going forward, I thought we created enough chances to have scored more than once, Shaun Miller looked bright again and had a couple of opportunities, so there are certainly positives to take, despite the defeat."