Chris Wilder praised his players, who overcame adversity, to beat Blackburn Rovers at Bramall Lane on Saturday.
In a game that ended with both sides having a player sent-off, three goals in eight second-half minutes proved decisive for United, who had Chris Basham red carded for two bookable offences.
And the manager felt the players and supporters united to grind out what in the end was a comfortable and deserved victory.
He remarked: "We were never going to take a backwards step, we wanted to leave two at the top of the pitch and we did.
"The two things that stand out for me were the discipline we showed when we changed the shape and the way the supporters got behind that shape, when we felt the sending off was unjust.
"Basham's tackle in the first-half was a great tackle, it was genuine and honest and I want my players to put their foot in, it's a great challenge."
Wilder continued: "The second booking is really unfortunate, he's moved his body, but that's enough about the referee's performance.
"We stepped on it when the numbers were evened out and there was only going to be one winner.
"Billy has been outstanding, he just keeps scoring and scoring, he's been excellent.
"Blackburn posed us problems, came with a positive approach and tried to win the game, it was a grind for us but we were happy to try and grind it out and we did that when we went down to ten-men."