A late Sander Berge goal gave Sheffield United some hope going into the second leg of their play-off semi-final against Nottingham Forest.
The away side took an early lead when Jack Colback scored on the rebound after Wes Foderingham had kept out Philip Zinckernagel's initial effort.
Brennan Johnson scored after a John Egan error to put the Reds in control.
With time almost up, Berge bundled home from a corner to set up a big second leg on Tuesday.
Forest were just two minutes away from leaving Sheffield with a richly deserved two-goal lead but will still start the second leg as favourites to reach Wembley.
After an even opening 10 minutes, Forest went in front when Sam Surridge got on to Joe Worrall's clipped ball into the inside-right channel and sent the ball into the middle for Zinckernagel. He should have scored but fired straight at Foderingham and, with Blades full-back Ben Osborn having slipped over, Colback was able to send the rebound home under no pressure.
Sheffield United responded well to the setback and Surridge was in the right spot to head off the line from Egan's header from John Fleck's inswinging corner.
That was as good as it got in the first 45 minutes for the home side though, as Forest totally dominated the rest of the half.
Ryan Yates headed wide from a great position after James Garner's cross found him unmarked in the middle, before keeper Foderingham saved well from Surridge and then did brilliantly to get up and keep out Johnson's follow-up header.
Foderingham had previously made separate saves from Surridge and Johnson, while the latter screwed an effort past the post, as the Blades clung on for the interval.
Paul Heckingbottom's men massively improved after the break and it was the visitors who had to weather a storm.
However, despite dominating the possession they could not force Brice Samba into a notable save and were then caught cold when substitute Joe Lolley robbed Egan of possession 30 yards from his own goal and drove forward, before the ball broke nicely for Johnson to sweep in a quality finish.
It could have got even worse for the Blades but Egan made a great block to deny Johnson after an enterprising run from Djed Spence, and Spence then sent a low drive into the side netting.
With the home fans streaming for the exits, their team won a late corner. Morgan Gibbs-White's centre was missed by Samba and Norway international Berge got the crucial touch to put the ball over the line.
Nottingham Forest were in the Championship relegation zone when Steve Cooper took over in September
Forest boss Steve Cooper has overseen a tremendous turnaround in the club's fortunes since taking over in September and he will now hope to guide them to Wembley success.
He took Swansea into the play-offs in both his seasons with the Welsh side but lost to Brentford in the semi-finals in the first year and the same opposition under the arch in 2021.
Forward Johnson repeated history with his goal, 19 years after father David scored in both legs against the same opposition in a play-off semi-final.
Despite the late setback, this Forest team look capable of doing what that one failed to and at least reach the final.
Sheffield United gave themselves some hope with an injury-time goal
Much was made before the tie about Sheffield United's poor record in play-offs, with no successes from their previous eight campaigns.
Boss Heckingbottom said he thought the record was "irrelevant" pre-match, but it felt as though his team were weighed down by expectation for much of a first half that they were incredibly lucky to only be a goal down after.
The Blades, who ended the regular season with a stunning 4-0 home win over champions Fulham, were again without a recognised striker because of injuries and their lack of a cutting edge was evident after the break when they had far more of the ball but rarely looked like scoring.
They will hope veteran skipper Billy Sharp can play at least some part in the second leg.