Nigel Clough was full of praise for his players following Sunday's entertaining 1-1 draw with Fulham in the FA Cup.
A late Hugo Rodallega strike cancelled out Chris Porter's first-half opener, but the Blades, who had skipper Michael Doyle dismissed early in the second period, were good value for a replay in the eyes of the Gaffer.
He remarked: "First and foremost I am immensely proud of the players for the effort and commitment they demonstrated from the first minute to the last.
"First-half I didn't think we were at our best despite getting our noses in front, but in the second-half, even after the red card, we played some good football and looked a real threat on the break.
"We said to the players at half-time we couldn't just defend for 45 minutes against Premiership opposition, we proved that at Villa and it was no different against Fulham, despite going down to ten.
"I thought we deserved a second goal and it would have been fantastic if we could have nicked it but thankfully we got in the hat for the fifth round draw."
On the game's major talking points, the Gaffer added: "I haven't seen the incident that led to the dismissal of Michael Doyle again yet, he admitted there was contact, but the lad went down easily.
"I thought there was less contact in that challenge than the one on Ryan Flynn in the penalty area. Ryan says the defender stood on the top of his foot - for me it was a certain penalty.
"Ray Wilkins (Fulham coach) said the referee was evening things up because they felt they should have had a penalty just after we had scored, but surely each decision should be judged on it's merit.
"Andre Marriner is one of the best referees and nicest blokes you could meet, but his decision making was frustrating at times throughout the tie."