Wilfried Zaha fired Crystal Palace into the Championship play-off final as the England winger's double sealed a 2-0 win over arch rivals Brighton in Monday's semi-final second leg.
Ian Holloway's team will face Watford at Wembley on 27 May with a lucrative place in the Premier League at stake thanks to the perfect leaving present from Zaha.
Zaha will join Manchester United at the end of the season after Palace agreed to sell him to the Premier League champions in a £15 million deal in January.
But the 20-year-old will have a chance to take Palace into the English top-flight before saying farewell after scoring twice in the second half to sink Brighton at the Amex Stadium.
After the first leg ended goalless at Selhurst Park on Friday, Brighton must have felt they had the advantage but they paid the price for wasting several opportunities to go in front before Zaha took charge.
"We are six undefeated but we came to this place and everyone said we wouldn't have a chance," Holloway said.
"I'm bursting with pride. We go to Wembley to take on Watford and who says we can't do that. Watford are a fantastic team but so are we."
Brighton boss Gus Poyet added: "We did something very good this season, but because of this play-off you go home terrible, feeling very sad. Sometimes it's not your turn and it was not to be.
"We were a bit nervous, but we created two unbelievable chances before they scored. Then the game got a bit crazy."
This derby clash couldn't match the drama of Watford's incredible second leg win against Leicester on Sunday, but there was still plenty of tension and intrigue as two old rivals slugged it out with so much at stake.
Brighton open strongly
Poyet's side dominated the early stages and Palace goalkeeper Julian Speroni had to keep out Will Buckley's drive before David Lopez's shot was deflected narrowly over.
Palace threatened when Jonny Williams shot just wide after being sent clean through by Aaron Wilbraham early in the second half.
But Brighton substitute Ashley Barnes twice came even closer to breaking the deadlock just a minute after climbing off the bench.
He latched onto Leonardo Ulloa's flick, only for Speroni to tip his shot onto the crossbar and from the resulting corner saw his header cleared off the line by Dean Moxey.
That proved the turning point as Holloway sent on Yannick Bolasie and the winger whipped over a brilliant cross that Zaha, escaping marker Wayne Bridge, met with a diving header past Tomasz Kuszczak in the 69th minute.
And Zaha sealed the win two minutes from full time when he turned Brighton defender Gordon Greer before thrashing his shot into the roof of the net.