Nigel Adkins was left to rue poor decision making as United slipped to a disappointing home defeat to in-form Wigan Athletic at Bramall Lane on Saturday.
The Latics scored twice in less than three second-half minutes to condemn the Blades to defeat, with Will Grigg netting a penalty and Conor McAleny adding a second moments later.
Reflecting on the loss, the Blades boss remarked: "It was poor decision making that leads to the penalty going against and unfortunately Wigan grabbed the initiative.
"Then we concede a second soon after from our own throw-in and that's bitterly disappointing. We speak a lot about the importance of controlling restarts and keeping possession but we didn't and got punished.
"At 2-0 down we had a mountain to climb against a good Wigan side and unfortunately we struggled to find a way of breaking them down."
Despite seeing George Long save a second Grigg penalty, the host could muster little in response and the Gaffer added: "Wigan play a certain way, they play with one up front and narrow in midfield as they look to keep possession, but we needed to be more ruthless when we turned the ball over up the field.
"Billy (Sharp) and Jose (Baxter) had chances in the first-half and we changed our shape a couple of times in a bid to get a grip of the game, but the turning point is the first penalty.
"It was always going to be a tight game, it was in the first-half, but we are still gifting goals and that is costing us."