Sharp completed his treble, his second of the season, nine minutes later to seemingly set United on their way to the top of the Championship, but Villa stormed back in stunning fashion with three goals late on.

Tyrone Mings, on his home debut, headed in in the 82nd minute to give Villa a lifeline and Tammy Abraham's 20th goal of the season made it 3-2. That set up a dramatic finale which saw Andre Green head home the equaliser four minutes into stoppage time.

Smith was left with mixed emotions after the incredible turnaround, saying: "We gave them a head start. We were poor on the ball and they started better than us and they scored from a set-piece goal.

"I thought we started the second half really well and then unfortunately the officials didn't do their job in the 52nd minute.

"It was a big momentum changer. I thought Billy Sharp was offside for the initial cross and the ball was in Kalinic's hands and I think the lad went in with his studs to score.

"Then Sharp scored a third goal and I thought the game would drift away. But I made a couple of changes. Mings scored his goal and then you could feel something had changed in the game .

"We maintained the comeback with Tammy Abraham scoring a second before Green came up for his equaliser."

While he was quick to laud his side's character, Smith admits they cannot afford to be left playing catch up like they were against their promotion rivals.

The former Sheffield Wednesday defender, whose Villa side remain eighth, said: "Three goals in the last 13 minute was really dramatic but we still have a lot to work on because we cannot start games like we started against Sheffield.

"What it does prove is that we have a lot of fighting spirit in the dressing room.

"Sheffield United will think they deserved to win but we showed a lot of character to come back to grab a point."

Bemused Blades boss Chris Wilder could hardly believe what he had witnessed.

He thought his side had three vital points in the bag – which would have taken them top – when Villa took full advantage of some defensive mistakes to snatch a dramatic draw.

He said: "I was in love with the game for 82 minutes but then something happened in the final 10 minutes.

"It was difficult to take playing in front of a 36,000 crowd. We were never going to have everything our own way. I wouldn't have expected it but we did for the majority of the game.

"Villa didn't play very well but the reason was the performance of my team.

"In the end it was individual errors at a time when I thought we could score a fourth goal when we looked really comfortable.

"We pushed back a good team but then there were three mistakes and suddenly you could see more urgency in the Villa side."

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