Rams paid price for not adding to lead
A superb 25-yarder from skipper Robbie Savage gave the Rams a 17th-minute lead and they had other opportunities to stretch their advantage.
They could not find a second goal and were punished when Lee Williamson equalised in stoppage time.
Clough took plenty of positives from the 1-1 draw despite the late disappointment.
"Only getting one goal in the first half when we had opportunities to get a second did us," he said.
"We did not have too many chances in the second half but we were pretty comfortable for the majority of it. I don't think the goalkeeper (Stephen Bywater) had too much to do.
"Then we got punished. The ball just dropped nicely in the box when really we should have been two or three up by then and out of sight.
"When we sit down and analyse it, the performance was very good again.
"The performance carried on from the Nottingham Forest game. To play a team in the play-off positions and play as well as we did, especially first half, certainly belied our League position.
"I thought the front two of Rob Hulse and Kris Commons led the line very well and everybody takes the lead from them when they defend from the front.
"Our two centre-halves were very good again – I thought Jake Buxton was the pick of them – and the back four as a unit looked good.
"We restricted Sheffield United to two or three shots.
"We want to try and keep it that way. That is our back four now and unless there is an injury or suspension, we will leave it."
Clough was also full of praise for Bywater.
"When they are putting balls in the box, which they did in the last 10 or 15 minutes, it is absolutely vital the keeper comes and collects. When the ball was up there, he came and looked imperious at times," said Clough.
"I thought one punch he made from a corner that was whipped in was very good.
"He was unlucky to concede the goal. It came off the lad's toe almost and crept in the corner, so Stephen was very unlucky not to get a second clean sheet on the spin."
Savage's second goal of the season was a cracker.
The ball dropped to him outside the box and the experienced midfielder caught it sweetly to give Mark Bunn no chance.
"He does not get many these days but when he does they are usually special," said Clough.
"He is as disappointed and frustrated as anyone it has not got us three points."
