Solly March's missed penalty saw Manchester United edge past Brighton to reach the FA Cup final with a 7-6 shoot-out win after a goalless semi-final draw at Wembley.
The Brighton winger was left inconsolable with the only miss of 14 spot-kicks, following a tense 120 minutes where either side could have felt they would have been worthy of returning to face Manchester City on June 3.
Brighton flew out of the blocks and saw Alexis Mac Allister pull David De Gea into an early fingertip save from a free-kick, but United improved as the half wore on and Bruno Fernandes and Anthony Martial both missed presentable chances in added time.
The Seagulls were inches from finally opening the scoring in the second period but Julio Enciso, the hero at Chelsea last weekend, was denied again by a flying De Gea stop before Danny Welbeck nodded wide from a corner. Substitute Jadon Sancho could have won it for Erik ten Hag's side late on, but lifted a curling effort just over the goalframe.
In extra-time, Marcus Rashford flashed an effort past the post with only Robert Sanchez to beat before Kaoru Mitoma's heavy touch denied him what seemed a certain last-minute winner - and after each of the first 12 penalties in the resulting shoot-out were scored, March's miss left Victor Lindelof to score the winning spot-kick and set United up for a shot at a second trophy this season.
How Man Utd squeezed past Brighton to set up final return
Brighton were looking to reach the FA Cup final for just the second time, after losing to Manchester United 40 years ago in a replay in their only previous appearance.
United, meanwhile, had the added motivation of bouncing back from their chastening Europa League exit in Seville on Thursday night, but were slow out of the blocks at Wembley and needed the fingertips of De Gea to deny Mac Allister from an early free-kick.
A succession of injury stoppages dented Brighton's early momentum, but Man Utd could only force Sanchez into a routine stop from Fernandes' curling effort.
Roberto De Zerbi would have been the happier manager until the closing minutes of the half, when United suddenly upped the pressure and nearly broke the deadlock. First Fernandes found himself clean through but shot wide, before a Martial lob, with Sanchez off his line, drifted agonisingly wide.
Antony's driving run and cut-back towards Martial moments after the interval might have signalled an improvement for the previously-anonymous Brazilian, but the game soon settled into the pattern of the first half, with Brighton pulling the strings.
A half-cleared corner fell for Enciso whose crisp, venomous first-time drive was tipped over by a springing De Gea save, before Welbeck nodded the second corner over from a matter of yards out when he really should have scored.
As had been the case before the break, United grew into proceedings helped largely by the introduction of Fred, whose industrious work finally helped them begin to control the midfield battle for the first time in the match.
Even so, they had only substitute Sancho's curler which just cleared the bar, and a tricky, low 20-yard effort from Antony to show for their new-found dominance.
There was little surprise there was no winning goal to be found, with the game level after 90 minutes just as Brighton's FA Cup final with Man Utd had ended four decades earlier.
The parallels continued but grew more cruel. Gordon Smith had missed a glorious chance in the final minute of added time in Brighton's first game that year, and this time Mitoma's heavy touch with only De Gea to beat denied him and the Seagulls the jubilation of a last-gasp winner at Wembley.
That was as close as either side came in the additional 30 minutes. Rashford should have done better after shaking off Joel Veltman but mis-hit a powerful drive well wide, while Marcel Sabitzer nodded a Sancho cross past the post.
With semi-final replays scrapped over 20 years ago that was to be the end of the similarities, bar the final result. After 12 perfect penalties, March blasted his spot-kick over the bar leaving victory in United's hands.
Up stepped Lindelof to send his side into their second final of the season, and repair some of the damage done by their limp Europa League exit to Sevilla on Thursday night.
De Zerbi: We deserved to win
Brighton head coach Roberto De Zerbi:
"We deserved to win because we played better and we had more chances to score. We suffered in the middle of the second half but for the other part of the game we commanded the play, we played in the other half of the pitch."
Asked what he said to Solly March, who missed in the shootout, De Zerbi said:
"Not too many words. I told him I was a player and made a lot of mistakes in penalties and it isn't a problem.
"He was one of the best players in terms of quality of performance on the pitch. I'm proud of him, especially [on Sunday]."
Ten Hag: Man Utd showed we can bounce back
Man Utd head coach Erik Ten Hag:
"It was the worst game of the season in Sevilla. You can't change it anymore but take the lessons for the future.
"What we've proved is we can deal with setbacks and bounce back between games, but now what we have to improve is bouncing back in a game, in difficult situations, in away stadiums, we have to show personality, carry on and stick to the plan.
"Even if we played a bad game, there was opportunities on Thursday night to bounce back in that game and get back into it. If you can fight three days after a defeat, you can also do that in a game. It's just controlling your emotions, sticking together and turning around the game.
"We are physically and mentally strong. We showed the character and personality to do that. I can tell you it's not so easy but we did it. We were determined to win this game."
What's next?
Brighton visit Nottingham Forest in the Premier League on Wednesday night; kick-off 7.30pm. Manchester United are back in action on Thursday evening at home to Tottenham; kick-off 8.15pm.
Brighton's remaining fixtures
April 26: Nottingham Forest (A) - Premier League, kick-off 7.30pm
April 29: Wolves (H) - Premier League, kick-off 3pm
May 4: Man Utd (H) - Premier League, kick-off 8pm, live on Sky Sports
May 8: Everton (H) - Premier League, kick-off 5.30pm
May 13: Arsenal (A) - Premier League, kick-off 3pm
May 18: Newcastle (A) - Premier League, kick-off 7.30pm
May 21: Southampton (H) - Premier League, kick-off 2pm
May 24: Man City (H) - Premier League, kick-off 8pm, live on Sky Sports
May 28: Aston Villa (A) - Premier League, kick-off 4.30pm
Man Utd's remaining fixtures
April 27: Tottenham (A) - Premier League, kick-off 8:15pm
April 30: Aston Villa (H) - Premier League, kick-off 2pm
May 4: Brighton (A) - Premier League, kick-off 8pm, live on Sky Sports
May 7: West Ham (A) - Premier League, kick-off 7pm
May 13: Wolves (H) - Premier League, kick-off 3pm
May 20: Bournemouth (A) - Premier League, kick-off 3pm
May 25: Chelsea (H) - Premier League, kick-off 8pm, live on Sky Sports
May 28: Fulham (H) - Premier League, kick-off 4.30pm
June 3: Man City (N) - FA Cup final, kick-off TBC
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