The win,which came after the game ended in a nil-all stalemate after extra time,set up the first-ever all-Manchester FA Cup final after City beat Sheffield United 3-0 on Saturday.
Solly March,Brighton’s seventh player to step up to the spot in the shootout,launched the ball over the bar before Victor Lindelof found the net to secure a 7-6 shootout victory for United.
The nail-biting finale was a fitting ending after 120 goalless minutes of wild swings in a game that see-sawed from end to end.
Sunday’s semi was a rematch of the 1983 final that saw Brighton lose to United in the south coast side’s only appearance in the decider.
Erik ten Hag’s United,12-times FA Cup winners,are chasing a cup double after winning the League Cup in February.
Manchester City – also alive in the Premier League and the Champions League – are chasing the treble.
The FA Cup final is on June 3 at Wembley.
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