David Brooks came off the bench to score the winner as Sheffield United won 2-1 at Leeds to go top of the Sky Bet Championship.
The 20-year-old was introduced in the 76th minute by Chris Wilder, and five minutes later he'd scored his first senior goal for the Blades to decide the game at Elland Road on Friday night.
Billy Sharp had put Sheffield United in front very early on before an emphatic Kalvin Phillips effort levelled the game at the break. But the Blades went on to secure victory and climb above Wolves in the table, although they or Cardiff could replace them at the top on Saturday.
Leeds made nine changes from their midweek defeat at Leicester in the Carabao Cup, while Sheffield United were unchanged.
Sheffield United have often been fast starters this season and it took them less than two minutes to take the lead through Sharp, who nodded home from close range after some fine build-up play from Leon Clarke and Mark Duffy, the latter finding his striker with a cross to the far post.
Leeds looked shell-shocked and the Blades continued to dominate the game, and Sharp had another great chance to double their lead on 26 minutes as he tried to prod home Clarke's cross from the left, but goalkeeper Andy Lonergan did well to deny him.
Leeds: Lonergan (6), Ayling (5), Pennington (5), Cooper (6), Anita (5), Phillips (6), O'Kane (5), Vieira (6), Saiz (7), Alioski (6), Lasogga (4)
Subs: Jansson (n/a), Hernandez (n/a), Grot (n/a)
Sheffield United: Blackman (7), Basham (7), Carter-Vickers (7), O'Connell (7), Baldock (7), Stevens (7), Coutts (7), Duffy (8), Fleck (7), Clarke (8), Sharp (7)
Subs: Lundstram (n/a), Brooks (7)
Man of the match: Mark Duffy
And that missed opportunity would prove costly for Wilder's side as Leeds levelled eight minutes later. It was Phillips who scored it in scintillating fashion, watching the ball drop out of the air after a poor clearance by Cameron Carter-Vickers, before volleying home from the edge of the area.
Sheffield United quickly rallied, though, and they had a glorious opportunity to take the lead again on the stroke of half-time. Leeds fell asleep while trying to organise themselves for a free-kick, and Duffy took it quickly to find Sharp in the middle, but Lonergan was alert enough to rush off his line and deny him an easy finish.
Samu Saiz then went close to putting Leeds ahead after 57 minutes as he had a shot from just outside the area, but it clattered the woodwork before bouncing clear.
The game could have gone either way but it was the introduction of Brooks that made the difference, as he made the most of another Duffy assist with a cool low strike to send the away fans wild.
Man of the match - Mark Duffy
Brooks may have stolen the headlines but everything good about Sheffield United came through Mark Duffy on Friday night. He set up both goals and was a constant thorn in the side of Leeds with his creative presence in the final third.
Thomas Christiansen: "I believe a draw would have been the fair result. The problem was we weren't on the pitch when we conceded the first goal, and when you start the game like that it's very difficult. The first half was bad but we were in the game at half-time.
"There had to be a change from everyone and we tried in the second half [to do that]. We had the possibility to go in front with [Saiz's shot that hit the post] and we finally lost the game, which I believe we didn't deserve to. But this is it now and we have to fight back ahead of Tuesday."
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Chris Wilder: "It's the best win but not the best performance. I thought we were decidedly average, we can keep the ball a lot better than what we've shown tonight and I think we were off the pace. But we looked for a bit of magic from someone to produce something to decide a tight game, and the young boy has done great to come on and get us into the lead.
"I wasn't too pleased with our performance, I thought it was one of the worst we've had all season, but I've said all along our character and togetherness takes us through."
Both sides are back in Championship action on Tuesday night, with Leeds hosting Derby and Sheffield United travelling to QPR.