Sheffield United regained second spot in League One as Ched Evans converted a late penalty to beat 10-man Hartlepool.
Evans took his goal tally to 10 in eight matches when he scored from the spot after Sam Collins had fouled him.
Pools' Peter Hartley had nearly opened the scoring but his effort was cleared off the line by Matthew Lowton.
Hartlepool, who have now scored only one goal in six matches, had Hartley dismissed for a second bookable offence following a foul on Michael O'Halloran.
The Blades had dropped down to third earlier in the day following Sheffield Wednesday's 2-0 win over Preston, but this win lifted United back above their city rivals.
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Hartlepool first-team coach Neale Cooper told BBC Tees:
"We were excellent today and it was one of our best performances against one of the teams going for automatic promotion. I feel really sorry for the players because we had a few chances.
"I can't ask for more than they gave and I was very proud of all the boys.
"The referee didn't give it (the penalty), the linesman gave it. I couldn't believe he gave it and we lost Peter Hartley, who was sent off for a second bookable offence. But if this group of boys give me that I can't ask for any more - they're a good bunch."
Sheffield United manager Danny Wilson told BBC Radio Sheffield:
"I think that's arguably the worst pitch I've seen in a long time at Hartlepool and to try to play football at times was difficult.
"It certainly didn't help the fluency of the passing and then take into account the wind as well.
"So we had to change some parts of our game, (in particular) our approach play was different at times."